JPEG saving options

CM
Posted By
carl_miller23
Sep 24, 2004
Views
1247
Replies
49
Status
Closed
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)

Thanks!!


Carl Miller

http://www.ezinfocenter.com/8557444

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

EG
Eric Gill
Sep 24, 2004
(Carl Miller) wrote in
news::

A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

Of course. It has to, to work on it.

What’s up with this, and practically speaking, should I be saving at 10 or 12?

You shouldn’t be re-saving a JPEG at all. Save your working copy in a lossless format, then use save for web to optimize the JPEG output for whatever you need it for.

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)
Thanks!!
CM
carl_miller23
Sep 24, 2004
On September 24 2004, Eric Gill wrote:
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the
"default" >> Maximum setting of 10, it compresses it to, say, about 900k. If I >> save it at the "maximum" Maximum setting of 12, I actually end up >> with a larger file than I started out with of about 3mb. Apparently >> it is uncompressing the original compressed jpeg?
Of course. It has to, to work on it.

What’s up with this, and practically speaking, should I be saving at 10 or 12?

You shouldn’t be re-saving a JPEG at all. Save your working copy in a lossless format, then use save for web to optimize the JPEG output for
whatever you need it for.
(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)

Thanks!!

Thank you mr. expert for totally NOT ansering my question. Didn’t I SAY I KNEW about lossy vs non-lossy compressions? Don’t you think that means I KNOW about saving my "work copy" in a non-lossy format? Now, re-read my post and if you can answer the question I asked, please do, but otherwise stop being a total lack of help. (Hint: The question is in one of the sentences that ends with a question mark.)

Sorry to sound pissy, but you gave me the exact type of NON-ANSWER I’ve been getting to this question for practically six months now. Apparently NO ONE knows the answer.


Carl Miller

http://www.ezinfocenter.com/8557444
NS
Nicholas Sherlock
Sep 24, 2004
Carl Miller wrote:
If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)

You say that you _know_ about lossy file formats, but your comments seem to suggest you have only a very basic understanding. Every time you open a JPEG, it’s decompressed. When it’s saved, it must be compressed again. No matter what compression level you set it to, you are losing information. When you set it to "12", the result is closer to the original file than if you set it to "10"

Cheers,
nicholas Sherlock
R
Rick
Sep 24, 2004
"Nicholas Sherlock" wrote in message
Carl Miller wrote:
If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)

You say that you _know_ about lossy file formats, but your comments seem to suggest you have only a very basic understanding. Every time you open a JPEG, it’s decompressed. When it’s saved, it must be compressed again. No matter what compression level you set it to, you are losing information. When you set it to "12", the result is closer to the original file than if you set it to "10"

Exactly. To put it another way, when you save a file in JPEG format, the compression routine doesn’t know or
care about any previous compression(s).

Rick
DD
David Dyer-Bennet
Sep 24, 2004
(Carl Miller) writes:

A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

Of course it is; that’s what loading it into photoshop does. And then if you save it, it recompresses it at whatever level you select.

What’s up with this, and practically speaking, should I be saving at 10 or 12?

I find essentially no use for either. For screen resolution, 8 is plenty, or even 5. For printing, I wouldn’t use jpeg. —
David Dyer-Bennet, <mailto:>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/> Dragaera/Steven Brust: <http://dragaera.info/>
N
nomail
Sep 24, 2004
Carl Miller wrote:

A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

Photoshop (or any other program) cannot edit images in compressed format, so yes, when you open an image it will be uncompressed.

What’s up with this, and practically speaking, should I be saving at 10 or 12?

All the information you’ve lost on the first compression, is lost forever. On the next compression you will loose information again, so if you insist in subsequent JPEG saves and you want to retain as much information as you can, you’ll have to use 12.


Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.nl/
EG
Eric Gill
Sep 24, 2004
(Carl Miller) wrote in
news::

On September 24 2004, Eric Gill wrote:
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the
"default" >> Maximum setting of 10, it compresses it to, say, about 900k. If I >> save it at the "maximum" Maximum setting of 12, I actually end up >> with a larger file than I started out with of about 3mb. Apparently >> it is uncompressing the original compressed jpeg?
Of course. It has to, to work on it.

What’s up with this, and practically speaking, should I be saving at 10 or 12?

You shouldn’t be re-saving a JPEG at all. Save your working copy in a lossless format, then use save for web to optimize the JPEG output for
whatever you need it for.
(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)

Thanks!!

Thank you mr. expert for totally NOT ansering my question. Didn’t I SAY I KNEW about lossy vs non-lossy compressions? Don’t you think that
means
I KNOW about saving my "work copy" in a non-lossy format?

That was, of course, why you asked about multiple saves in JPEG.

Now, re-read
my post and if you can answer the question I asked, please do, but otherwise stop being a total lack of help. (Hint: The question is in
one
of the sentences that ends with a question mark.)

Sorry to sound pissy,

Oh, I’m sure.

but you gave me the exact type of NON-ANSWER I’ve
been getting to this question for practically six months now.
Apparently
NO ONE knows the answer.

The answer is simply that you shouldn’t be re-saving in JPEG format.

It’s not my problem that you don’t like the answer, and getting pissy because you hold a misconception is stupid.
AM
Andrew Morton
Sep 24, 2004
The higher the setting, the more accurately it records the image, including the distortions caused by the previous jpeg encoding. Higher setting=>more detail will be recorded=>bigger file.

Andrew
T
tacitr
Sep 24, 2004
I’ve noticed that if I open
a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb.

Yes, of course.

You open a JPEG. It is now uncopressed. it is impossible to display or edit a JPEG without uncompressing it.

You save it. Now it is compressed as though it had never been compressed to begin with. The higher the quality, the bigger the file.

Apparently it is uncompressing the
original compressed jpeg?

Yes, of COURSE it is! If it didn’t uncompress it, how could it show you the image on the screen?

What’s up with this…

Let’s say you have a JPEG compressed at the lowest possible quality. it’s a tiny file. You open it and it’s uncompressed. You Save As. You set the highest possible quality. It will be a bigger file, because it has been uncompressed, and then recompressed again with higher qualiy setting.

Of course, when you open and then re-save a JPEG, you lose more information. You open and re-save again, you lose still more information. Every time you open and re-save, the quality goes down, and down, and down; the loss is cumulative.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
M
metpx3c
Sep 26, 2004
(Carl Miller) wrote in message news:…
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)
Thanks!!

I’ve had the exact questions. I was hoping for a straight forward answer, but I must agree with Carl, no one directly answered the questions; e.g. what about Max = 10 but 12 is available. Why is 12 larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.
B
bagal
Sep 26, 2004
FWIW I don’t know exactly either

Urban myths are:
resaving JPEG to JPEG at low levels cummulatively reduces (?) image size and hence quality
JPEG compression algorithms are independent steps
for example
(a)image save at JPEG level 5 then image reopened and saved at JPEG level 12 => this will not return the image to its original appearance because JPEG is lossy BUT saving and resaving at JPEG level 12 will not cummulatively reduce (?) image quality

(b) image saved a JPEG level 5 then image reopned and saved at JPEG level 5 => a second application of the JPEG compression algorithms => a further loss in image quality

I suppose (a) and (b) may be tested empirically (I can be bothered at the mo’)

My own preference on working images is to take JPEG to PSD and keep everytthing in PSD form flattening out into JPEG at level 12 setting until I am pleased with result. Mike will probably confirm that I am easily pleased with results – possibly too easily pleased LOL

Saving to JPEG at anyother setting – I try to do this from the PSD file rather than JPEG to JPEG (I can’t remember why tho 🙂

Artie

"Martin" wrote in message
(Carl Miller) wrote in message
news:…
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)
Thanks!!

I’ve had the exact questions. I was hoping for a straight forward answer, but I must agree with Carl, no one directly answered the questions; e.g. what about Max = 10 but 12 is available. Why is 12 larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.
R
Rick
Sep 26, 2004
"Martin" wrote in message
(Carl Miller) wrote in message news:…
A straight-forward answer to this might be out there, but I haven’t found it yet. (All file sizes are approximations, but representative of actual experience.)

When saving JPEG’s, the Quality drop-down menu gives you the choice of Low, Medium, High, Maximum. Choosing Maximum gives a setting of 10. However, you can increase the setting to 12. I’ve noticed that if I open a JPEG that is, say, about 1.3mb and save it at the "default" Maximum setting of 10, it compresses it to, say, about 900k. If I save it at the "maximum" Maximum setting of 12, I actually end up with a larger file than I started out with of about 3mb. Apparently it is uncompressing the original compressed jpeg?

What’s up with this, and practically speaking, should I be saving at 10 or 12?

(Take it as read that I know about tif being non-lossy, and jpeg being lossy, etc. I’m just wondering about this Photoshop jpeg Quality thing.)
Thanks!!

I’ve had the exact questions. I was hoping for a straight forward answer, but I must agree with Carl, no one directly answered the questions; e.g. what about Max = 10 but 12 is available. Why is 12 larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.

It’s been explained to you in plain English. What part of this do you not understand:

The JPEG compression routine doesn’t know or care whether an image has been previously compressed. In other words, when you JPEG compress an image, the routine doesn’t know or care what the original file size was, or what quality settings were used for previous compressions. At quality 12 you’re getting a less compressed image, therefore larger in size, although it will still be compressed, and will still be lossy relative to the original.

Rick
T
tacitr
Sep 26, 2004
Why is 12
larger that the original (details)?

Very, very simple.

You have an image. Let us say for the sake of example that the image, when UNCOMPRESSED, is one megabyte.

You save it as a JPEG. You use quality, say, 4. It saves to about 200 kilobytes.

You open the JPEG, It uncompresses. The image is 1 megabyte uncompressed.

You save it as JPEG with quality 12. It compresses again. You saved it with a higher quality so this time it compresses to 500 kilobytes.

Make sense?


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
T
tacitr
Sep 26, 2004
Why is 12
larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.

It’s very, very simple, and has already been explained.

Let us say you have an image that is 1 megabyte in size uncompresssed. Let’s say you save it as a JPEG with quality 4. So it saves to a file that’s, for instance, about 150 K in size.

Now you open that 150 K JPEG. It uncompresses. Now it is 1 megabyte again.

Now you save it again. You save as JPEG with quality 12. So it compresses again, this time to 500 kilobytes.

Make sense?


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
DD
David Dyer-Bennet
Sep 27, 2004
(Martin) writes:

I’ve had the exact questions. I was hoping for a straight forward answer, but I must agree with Carl, no one directly answered the questions; e.g. what about Max = 10 but 12 is available. Why is 12 larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.

That second question *was* specifically answered, I thought, but I’ll go through it again.

When you open an image in Photoshop, it reads whatever format the image file is originally in and decodes it into computer memory where it’s stored as an uncompressed bitmap. (Yes, if any of the Photoshop programmers hang out here I know there are additional complexities, not nearly well enough to explain them, so I’m not trying.) This is the *full-sized* bitmap — if it’s a 1600×1200 digital original in 24-bit color, that’s a 5,760,000 byte image, even though the jpeg might have been 512KB.

So, there’s this bitmap image in memory. Big. You edit it some, change various bits, whatever. (Or just leave it alone, not change any bits).

Now you tell Photoshop to save the image. It pops up the dialog for you to select the quality level, and then starts coding the image into a jpeg using the setting you gave it and writing the result to disk.

If the new quality level you give is the same as was used in the original jpeg, the resulting file will be about the same size (if you haven’t changed the bitmap extensively). If you pick a higher quality level, the resulting file will be larger — it won’t compress it as much. If you pick a lower quality level, the resulting file will be smaller — it will compress more.

(The photoshop quality levels are a layer above the actual parameters to the jpeg compression algorithm, by the way; that’s why every program has a different way of expressing degree of jpeg compression, and they’re not easy to compare to each other.)

Have I managed to make it make sense? Sorry if I still haven’t.

As to your *first* question, about the "level 12" quality, I think I know a tiny bit about why that’s so. I believe that the range was 1-10 in earlier versions. They decided to add some options at the top, and rather than changing the meaning of the previous options, they just added more numbers (11 and 12) to describe the new options. I *don’t* really know exactly how those differ from 10, though. —
David Dyer-Bennet, <mailto:>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/> Dragaera/Steven Brust: <http://dragaera.info/>
CM
carl_miller23
Sep 27, 2004
On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG. (MPIX for instance, a division of Miller, a HIGHLY RESPECTED company in the professional photography world.)

See, I LOVE the internet because people who DON’T KNOW the answer to the question always seem to feel the need to phrase something that they DO KNOW so that it SOMEHOW REMOTELY RELATES to the original question, thereby SEEMING TO PROVE to themselves and everyone listening that they DO INDEED KNOW SOMETHING!


Carl Miller

http://www.ezinfocenter.com/8557444
C
Clyde
Sep 27, 2004
Tacit wrote:
Why is 12
larger that the original (details)?

Very, very simple.

You have an image. Let us say for the sake of example that the image, when UNCOMPRESSED, is one megabyte.

You save it as a JPEG. You use quality, say, 4. It saves to about 200 kilobytes.

You open the JPEG, It uncompresses. The image is 1 megabyte uncompressed.
You save it as JPEG with quality 12. It compresses again. You saved it with a higher quality so this time it compresses to 500 kilobytes.
Make sense?

No problem, as long as you understand that Photoshop isn’t restoring any of that lossy information that JPEG got rid of when it compressed. PS is only opening what is there.

However, it opens everything the same. So, this shade of red takes up just as much memory as that shade of red. That is true even if the shades of red are the same. That’s why the memory size is the big size, not the little file size. The file size makes certain shades of red all the same and then treats them as one small piece of data rather than all of them separately. [Highly simplified]

So, if PS were just cutting down the number of reds when it resaves in JPEG, the theory it wouldn’t change a thing. Of course, YOU may have changed something in the picture. Then it isn’t changing the same thing. So, it compresses on top of the previous.

Also, you don’t know what settings were used for the first JPEG compression. The odds are that yours won’t be the same. So, PS will be compressing it differently. That means that it’s likely to add to lossiness.

Now, if those losses mean anything or are actually visible are another question completely. You will have to test that to your own satisfaction.

Clyde
X
Xalinai
Sep 27, 2004
Carl Miller wrote:

On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG. (MPIX for instance, a division of Miller, a HIGHLY RESPECTED company in the professional photography world.)

See, I LOVE the internet because people who DON’T KNOW the answer to the question always seem to feel the need to phrase something that they DO KNOW so that it SOMEHOW REMOTELY RELATES to the original question, thereby SEEMING TO PROVE to themselves and everyone listening that they DO INDEED KNOW SOMETHING!

Whatever you do, you should handle the decision whether it is time to save as JPG with the same care as you would the decision to save a text document in a printer’s native format.

You surely would keep a text version – so keep an uncompressed version of your images.

When you save an image that is in your computer’s memory as a JPG image the compression algorithm does not know anything about the image expect that it is a rectangular array of pixels.

IF your image was overcompressed earlier, saving at a lower compression setting will take care to represent all detail fount in the currently loaded image – including the artifacts created by the earlier save process. So your image file may become bigger – it won’t become better.

If you use very low compression you can be lucky that untrained eyes do not see the degradation even avter several saves – and if you send images to printing services that are sufficiently large for a high number of pixels per inch then artifacts will be small enough to become invisible. As JPG artifacts occur in blocks of 8×8 pixels, with 300dpi your artifact size will be 37.5 blocks per inch – not everybody will notice them.

Printing services love JPG as it reduces their transfer volume.

Michael
T
tacitr
Sep 27, 2004
So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG. (MPIX for instance, a division of Miller, a HIGHLY RESPECTED company in the professional photography world.)

MPIX is a consumer-level printing service that takes images online. They prefer JPEG because it’s easiest to transfer JPEG images over the Web, and as a consumer-level service, they know that the JPEG artifacts will probably not be noticeable or objectionable to their clients.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
B
bagal
Sep 27, 2004
Nice concise & nto the point

good answer!

Artie

"David Dyer-Bennet" wrote in message
(Martin) writes:

I’ve had the exact questions. I was hoping for a straight forward answer, but I must agree with Carl, no one directly answered the questions; e.g. what about Max = 10 but 12 is available. Why is 12 larger that the original (details)? If someone who really understand P/Shop JPEG save routing could/would answer it would be appreciated.

That second question *was* specifically answered, I thought, but I’ll go through it again.

When you open an image in Photoshop, it reads whatever format the image file is originally in and decodes it into computer memory where it’s stored as an uncompressed bitmap. (Yes, if any of the Photoshop programmers hang out here I know there are additional complexities, not nearly well enough to explain them, so I’m not trying.) This is the *full-sized* bitmap — if it’s a 1600×1200 digital original in 24-bit color, that’s a 5,760,000 byte image, even though the jpeg might have been 512KB.

So, there’s this bitmap image in memory. Big. You edit it some, change various bits, whatever. (Or just leave it alone, not change any bits).

Now you tell Photoshop to save the image. It pops up the dialog for you to select the quality level, and then starts coding the image into a jpeg using the setting you gave it and writing the result to disk.
If the new quality level you give is the same as was used in the original jpeg, the resulting file will be about the same size (if you haven’t changed the bitmap extensively). If you pick a higher quality level, the resulting file will be larger — it won’t compress it as much. If you pick a lower quality level, the resulting file will be smaller — it will compress more.

(The photoshop quality levels are a layer above the actual parameters to the jpeg compression algorithm, by the way; that’s why every program has a different way of expressing degree of jpeg compression, and they’re not easy to compare to each other.)

Have I managed to make it make sense? Sorry if I still haven’t.
As to your *first* question, about the "level 12" quality, I think I know a tiny bit about why that’s so. I believe that the range was 1-10 in earlier versions. They decided to add some options at the top, and rather than changing the meaning of the previous options, they just added more numbers (11 and 12) to describe the new options. I *don’t* really know exactly how those differ from 10, though. —
David Dyer-Bennet, <mailto:>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/>
<http://www.dd-b.net/dd-b/SnapshotAlbum/>
Dragaera/Steven Brust: <http://dragaera.info/>
EG
Eric Gill
Sep 28, 2004
(Carl Miller) wrote in
news::

On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

Not ever, really golly-gosh. Not if you have any control over the situation.

So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG.

Are they forcing you to make multiple JPEG saves, or have you simply not thought this through?

(MPIX for instance, a
division of Miller, a HIGHLY RESPECTED company in the professional photography world.)

See, I LOVE the internet because people who DON’T KNOW the answer to the question always seem to feel the need to phrase something that they DO KNOW so that it SOMEHOW REMOTELY RELATES to the original question, thereby SEEMING TO PROVE to themselves and everyone listening that they DO INDEED KNOW SOMETHING!

Yes, it seems you have a serious issue there.

If a beer doesn’t help, perhaps you should seek therapy.
CM
carl_miller23
Sep 28, 2004
On September 26 2004, David Dyer-Bennet wrote:
I believe that the range was
1-10 in earlier versions. They decided to add some options at the top, and rather than changing the meaning of the previous options, they just added more numbers (11 and 12) to describe the new options. I *don’t* really know exactly how those differ from 10, though.

THANK YOU! Whether that is actually correct or not (I REALLY APPRECIATE the "I believe" disclaimer. Most people would just proceed on as if they knew it as Truth.) that is the MOST DIRECT AND APPLICABLE ANSWER in well over 6 months!


Carl Miller

http://www.ezinfocenter.com/8557444
B
bigbopper
Sep 28, 2004
in article , Carl Miller at
wrote on 09/27/2004 8:26 PM:

that is the MOST DIRECT AND APPLICABLE ANSWER in well
over 6 months!

What a cry baby you are.
DD
David Dyer-Bennet
Sep 28, 2004
Eric Gill writes:

(Carl Miller) wrote in
news::

On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

Not ever, really golly-gosh. Not if you have any control over the situation.

Even *I* will call that excessive. Slightly.

In particular, if your camera produces JPEG output, then to really follow that rule would mean you never produced a JPEG for web display. Which is obviously dumb.

So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG.

Are they forcing you to make multiple JPEG saves, or have you simply not thought this through?

The point is *sequences* of jpeg saves. Other than in emergencies, *I’ll* save to jpeg exactly *once*, and never touch that file again (I might *replace* it with a new version, reworked from the original or a losslessly-saved intermediate). If I started with a jpeg file from the camera, that’s a "resave", though.

David Dyer-Bennet, <mailto:>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/> Dragaera/Steven Brust: <http://dragaera.info/>
R
Rick
Sep 28, 2004
"Carl Miller" wrote in message
On September 26 2004, David Dyer-Bennet wrote:
I believe that the range was
1-10 in earlier versions. They decided to add some options at the top, and rather than changing the meaning of the previous options, they just added more numbers (11 and 12) to describe the new options. I *don’t* really know exactly how those differ from 10, though.

THANK YOU! Whether that is actually correct or not (I REALLY APPRECIATE the "I believe" disclaimer. Most people would just proceed on as if they knew it as Truth.) that is the MOST DIRECT AND APPLICABLE ANSWER in well over 6 months!

Actually four different people have given you the exact same answer. David simply phrased it in a way your little pea brain could wrap itself around.

Rick
S
Scraphead
Sep 28, 2004
MPIX is a consumer-level printing service that takes images online. >They
prefer
JPEG because it’s easiest to transfer JPEG images over the Web, and as a consumer-level service, they know that the JPEG artifacts will probably not
be
noticeable or objectionable to their clients.
Rinky Dink

How hard is it to do all of your photo reworks in psd format and then save the final that goes to the printer in jpg, so it doesn’t have to be resized at all?
And, if you use Corel Draw or a program that will import psd files and supply the printer with a hi-res pfd file of your final project, you should never even have to see a jpg. To some, this may even be rinky dink, but a hell of a lot better than what is described above!
S
Scraphead
Sep 28, 2004
"David Dyer-Bennet" wrote in message
The point is *sequences* of jpeg saves. Other than in emergencies, *I’ll* save to jpeg exactly *once*, and never touch that file again (I might *replace* it with a new version, reworked from the original or a losslessly-saved intermediate). If I started with a jpeg file from the camera, that’s a "resave", though.
Once out of the camera, I convert it to a psd file for working on. Am I losing anything there? I’ve been doing that since last year when this had been brought up, for the millionth time

<http://dragaera.info/>
S
Scraphead
Sep 28, 2004
"Rick" wrote in message n
When you set it to "12", the result is closer to the original file than
if
you set it to "10"

Exactly. To put it another way, when you save a file in JPEG format, the compression routine doesn’t know or
care about any previous compression(s).

Rick
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!
B
bhilton665
Sep 28, 2004
When you set it to "12", the result is closer to the original file than if you set it to "10"

From: "Scraphead" Watashee@{deletethis}one.net
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

Every "soul" who saves jpegs for the web will soon discover that at moderate mid-level settings well below 10 or 12 you have a much smaller file size with acceptable quality, so people can look at your images without lengthy waits for downloads.
T
tacitr
Sep 28, 2004
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

Yes, there are many times when you want to save a JPEG with less quality–for example, for the Web.

The JPEG file format was created for situations where file size is critical and file quality is not important. The Web is one such situation. There are many times when a JPEG saved at maximum quality is just plain too big for a Web site.

Only use JPEG if you *have to*–if you absolutely must have a small file, and quality isn’t important. Never save a JPEG if you do not have to have a JPEG. ("JPEG is the only kind of file I know about" does not qualify as "have to.")


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
S
Scraphead
Sep 29, 2004
Aren’t you supposed to be using gif’s for the web? Isn’t that what they are designed for??
If not, what. They’re pretty useless,otherwise.

"Bill Hilton" wrote in message
When you set it to "12", the result is closer to the original file than if you set it to "10"

From: "Scraphead" Watashee@{deletethis}one.net
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

Every "soul" who saves jpegs for the web will soon discover that at
moderate
mid-level settings well below 10 or 12 you have a much smaller file size
with
acceptable quality, so people can look at your images without lengthy
waits for
downloads.

H
Hecate
Sep 29, 2004
On Tue, 28 Sep 2004 00:51:31 -0500, David Dyer-Bennet
wrote:

Eric Gill writes:

(Carl Miller) wrote in
news::

On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

Not ever, really golly-gosh. Not if you have any control over the situation.

Even *I* will call that excessive. Slightly.

In particular, if your camera produces JPEG output, then to really follow that rule would mean you never produced a JPEG for web display. Which is obviously dumb.

Look at what he’s saying *resaving" NOT final save.


Hecate – The Real One

veni, vidi, reliqui
B
bhilton665
Sep 29, 2004
From: "Scraphead" Watashee@{deletethis}one.net
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

"Bill Hilton" wrote in message

Every "soul" who saves jpegs for the web will soon discover that at moderate mid-level settings well below 10 or 12 you have a much smaller file size with acceptable quality, so people can look at your images without lengthy waits for downloads.

From: "Scraphead" Watashee@{deletethis}one.net
Aren’t you supposed to be using gif’s for the web?

Try saving a photo image as a 16 color gif (or even a full color gif) and see for yourself 🙂 Jpegs have many more shades and tones and are much better for photos.

Isn’t that what they are designed for??

Nope.

If not, what.

Line art, cartoons, limited color images …

They’re pretty useless,otherwise.

Do you know ANYTHING about web design and using the right file formats?
O
orchid
Sep 29, 2004
"Bill Hilton" wrote in message
When you set it to "12", the result is closer to the original file than if you set it to "10"

From: "Scraphead" Watashee@{deletethis}one.net
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

Every "soul" who saves jpegs for the web will soon discover that at
moderate
mid-level settings well below 10 or 12 you have a much smaller file size
with
acceptable quality, so people can look at your images without lengthy
waits for
downloads.

Scraphead <Watashee@{deletethis}one.net> wrote:

Aren’t you supposed to be using gif’s for the web? Isn’t that what they are designed for??
If not, what. They’re pretty useless,otherwise.

GIFs are designed for images which use a lot of solid colors (like clip art) and are limited to 256 colors. JPEGs are designed for continuous tone images like photographs. Each format is optimized to create smaller files for a different type of image. Unfortunately, most people aren’t aware of these differences and tend to use one format or the other exclusively often creating bigger than necessary files or less attractive files.

If you test the Photoshop "save for web" option, you can use the 4-up tab to compare the differences in various types of images saved as different file types. For instance, try making a solid color square and saving setting it to GIF in one panel and jpeg in another. The lowest quality jpeg compression will likely take longer to download than saving it as a GIF. Try the same with a photograph.

Orchid
T
tacitr
Sep 29, 2004
Aren’t you supposed to be using gif’s for the web? Isn’t that what they are designed for??

The GIF specification was designed before the Web existed.

You use both GIF and JPEG for the Web. You use GIF if you need only a few colors, such as for line drawings or for computer graphics, or if you need transparency. You use JPEG for photographic images with lots of color.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
B
bagal
Sep 29, 2004
I may need therapy but I’d love the beer

Arty

"Eric Gill" wrote in message
(Carl Miller) wrote in
news::

On September 24 2004, Eric Gill wrote:
The answer is simply that you shouldn’t be re-saving in JPEG format.

Not ever?

Not ever, really golly-gosh. Not if you have any control over the situation.

So how about explaining this to most of the printing services that PREFER you submit your digital files in JPEG.

Are they forcing you to make multiple JPEG saves, or have you simply not thought this through?

(MPIX for instance, a
division of Miller, a HIGHLY RESPECTED company in the professional photography world.)

See, I LOVE the internet because people who DON’T KNOW the answer to the question always seem to feel the need to phrase something that they DO KNOW so that it SOMEHOW REMOTELY RELATES to the original question, thereby SEEMING TO PROVE to themselves and everyone listening that they DO INDEED KNOW SOMETHING!

Yes, it seems you have a serious issue there.

If a beer doesn’t help, perhaps you should seek therapy.
EG
Eric Gill
Sep 29, 2004
"Artie" wrote in gui.ntli.net:

I may need therapy but I’d love the beer

Well, there’s always…beer therapy.
S
Scraphead
Sep 29, 2004
"Bill Hilton" wrote in message
From: "Scraphead" Watashee@{deletethis}one.net
Why do they even bother with an adjustable scale then? I would think that there is not a soul who would want to save a file with less quality!

"Bill Hilton" wrote in message

Every "soul" who saves jpegs for the web will soon discover that at moderate mid-level settings well below 10 or 12 you have a much smaller file size with acceptable quality, so people can look at your images without lengthy waits for downloads.

From: "Scraphead" Watashee@{deletethis}one.net
Aren’t you supposed to be using gif’s for the web?

Try saving a photo image as a 16 color gif (or even a full color gif) and
see
for yourself 🙂 Jpegs have many more shades and tones and are much better
for
photos.

Isn’t that what they are designed for??

Nope.

If not, what.

Line art, cartoons, limited color images …

They’re pretty useless,otherwise.

Do you know ANYTHING about web design and using the right file formats?

If I did know everything I would be TELLING, not ASKING! See the question marks after my QUESTIONS?
Obviously, I’m trying to learn this stuff. There was just a looong recent thread on here where all the so-called NG know-it-alls were saying what I’m repeating. It was generally agreed, (um, not even agreed, they were hammering it down our throats) here that tiffs are best for line art and such. Gifs were computer/monitor/web related and jpgs are pieces of crap that never should have been invented. Where are they all now? lol.

And, for Christ’s sake, quit being so condescending.
S
Scraphead
Sep 29, 2004
Thanks Tacit.
"Tacit" wrote in message
Aren’t you supposed to be using gif’s for the web? Isn’t that what they
are
designed for??

The GIF specification was designed before the Web existed.
You use both GIF and JPEG for the Web. You use GIF if you need only a few colors, such as for line drawings or for computer graphics, or if you need transparency. You use JPEG for photographic images with lots of color.
How do tiffs compare, given that jpgs lose integrity as they are messed with?
At any rate, I guess it’s safe to say, I can’t get hurt doing photo work in psd and saving to jpg at the final piece?
T
tacitr
Sep 29, 2004
It was generally agreed, (um, not even agreed, they were hammering it down our throats) here that tiffs are best for line art and such. Gifs were computer/monitor/web related and jpgs are pieces of crap that never should have been invented.

TIFFs are best for any image that is intended for professional printing, for general use, or for other situations where file quality is important and file size is not important.

GIF is intended for images that contain few colors and are not photographic in nature, and are to be used online or in other situations where file size is important. It works well for line art that is not intended to be printed, and for computer graphics. it is only for on-screen use. It is not good for photographic images.

JPEG is intended for photographic images in cases where file quality is not important but file size is important. It makes very small files. It does this by deliberately degrading the quality of the image. Because file size is important on the Web, JPEG is used on the Web.

TIFF: Good general-purpose format. Good for print. Not good for the Web, because the files are big.

GIF: Not good for print. Not good for photographic images. Few colors. Good for simple drawings or line art that will only be seen on a computer screen. Good for the Web.

JPEG: Good for photographic images where file size is more important than file quality. Good for the Web. Not good for general use, because it degrades image quality.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
T
tacitr
Sep 29, 2004
How do tiffs compare, given that jpgs lose integrity as they are messed with?

TIFF is an ideal format for general use. In fact, TIFF is one of the preferred formats for professional printing and pre-press use. If you want a good format for saving just about any kind of image, use TIFF unless you have a specific reason to use some other format.

At any rate, I guess it’s safe to say, I can’t get hurt doing photo work in psd and saving to jpg at the final piece?

As long as you are not editing and re-saving JPEG, that’s correct.

What do you plan to do with the final piece? If you plan to put it on the Web, use JPEG. If you plan to do anything else with it–print it, place it in another program, whatever–use TIFF.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
B
bhilton665
Sep 29, 2004
From: "Scraphead" Watashee@{deletethis}one.net

There was just a looong recent thread on here where all the so-called NG know-it-alls were saying what I’m repeating.

Not exactly.

It was generally agreed, (um, not even agreed, they were hammering it down our throats) here that tiffs are best for line art and such. Gifs were computer/monitor/web related and jpgs are pieces of crap that never should have been invented. Where are they all now? lol.

Yes, they are probably LOL … you misunderstood what was written. The "experts" as you call them said not to save your working files as jpegs because every time you save the files get compressed again and eventually you lose information, whereas tiffs are lossless. This is not the same as saying there is no use for jpegs at all … they are the best solution for creating web images of photos.

Bill
T
tacit
Sep 29, 2004
in article , Scraphead at
Watashee@{deletethis}one.net wrote on 09/29/2004 1:22 PM:

And, for Christ’s sake, quit being so condescending.

Or what will you do?
S
Scraphead
Sep 29, 2004
Excellent reply,
Thanks.

"Tacit" wrote in message
It was generally agreed, (um, not even agreed, they were hammering it down our throats) here that tiffs are best for line art and such. Gifs were computer/monitor/web related and jpgs are pieces of crap that never should have been invented.

TIFFs are best for any image that is intended for professional printing,
for
general use, or for other situations where file quality is important and
file
size is not important.

GIF is intended for images that contain few colors and are not
photographic in
nature, and are to be used online or in other situations where file size
is
important. It works well for line art that is not intended to be printed,
and
for computer graphics. it is only for on-screen use. It is not good for photographic images.

JPEG is intended for photographic images in cases where file quality is
not
important but file size is important. It makes very small files. It does
this
by deliberately degrading the quality of the image. Because file size is important on the Web, JPEG is used on the Web.

TIFF: Good general-purpose format. Good for print. Not good for the Web, because the files are big.

GIF: Not good for print. Not good for photographic images. Few colors.
Good for
simple drawings or line art that will only be seen on a computer screen.
Good
for the Web.

JPEG: Good for photographic images where file size is more important than
file
quality. Good for the Web. Not good for general use, because it degrades
image
quality.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
S
Scraphead
Sep 29, 2004
"Bill Hilton" wrote in message
From: "Scraphead" Watashee@{deletethis}one.net

Yes, they are probably LOL … you misunderstood what was written. The "experts" as you call them said not to save your working files as jpegs
because
every time you save the files get compressed again and eventually you lose information, whereas tiffs are lossless. This is not the same as saying
there
is no use for jpegs at all … they are the best solution for creating web images of photos.

Bill
Got it, sounds like a couple of options, anyway.
S
Scraphead
Sep 29, 2004
"Tacit" wrote in message
What do you plan to do with the final piece? If you plan to put it on the
Web,
use JPEG. If you plan to do anything else with it–print it, place it in another program, whatever–use TIFF.


Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html
Actually, I do a pretty good business designing ads.
I do a lot of them in corel draw and all of the photos I import are psd files. The publishers that I deal with all request hi-res pdf file, which Corel can produce.
To most PS diehards I’m sure that sounds quite bohemian, but when a mag prints at 240 dpi and I supply an 800 pdf file, it seems to work. The ads look great printed so what the hey!
Here’s one. It’s a "jpg", but gives you an idea
S
Scraphead
Sep 30, 2004
"tacit" wrote in message
in article , Scraphead at
Watashee@{deletethis}one.net wrote on 09/29/2004 1:22 PM:

And, for Christ’s sake, quit being so condescending.

Or what will you do?

Thank You!
CM
carl_miller23
Sep 30, 2004
On September 28 2004, "Rick" wrote:
Actually four different people have given you the exact same answer. David simply phrased it in a way your little pea brain could wrap itself around.

No, actually, his was just the first one I saw.
CM
carl_miller23
Sep 30, 2004
On September 29 2004, (Tacit) wrote:
The GIF specification was designed before the Web existed.

This is true, technically, but keep in mind who GIF was designed by (Compuserve) and why (in order to transmit images).


Carl Miller

http://www.ezinfocenter.com/8557444

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