image size and dpi

S
Posted By
steve
Apr 26, 2004
Views
551
Replies
13
Status
Closed
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes the image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

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J
jaSPAMc
Apr 26, 2004
On Mon, 26 Apr 2004 17:14:37 +0200, "steve"
found these unused words floating about:

Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes the image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

–Some Good People–
www.saHOSTplus.com
Full cPanel hosting starting $2.95 a month
Use this coupon (Group 50% OFF) and receive 50%
off from all hosting and reseller hosting packages
offer expire on 2004/05/01

F1 => index => resize.
PJ
Paul J Gans
Apr 26, 2004
steve wrote:
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes the image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

Perhaps it will help if I take a shot at explaining what is going on here.

Your original image contains a certain number of pixels across and a certain number down. That’s all that you image has. It knows nothing about size.

For the sake of argument let us assume that you have an image that is 1024 pixels across and 768 down.

If you tell Photoshop that you want this image to be at 256 dpi *AND* if you have the "resample image" box unchecked, it will tell you that the image is 4.00 inches across and 3.00 inches down.

If you tell Photoshop that you want this image to be at 128 dpi *AND* if you have the "resample image" box unchecked, it will tell you that your image is 8.00 inches across and 6.00 inches down.

In neither case has the number of pixels changed.

Alternatively you could set the dimensions and see what dpi you would get.

On the other hand, if you check the "resample image" box, Photoshop will attempt to add or subtract pixels as needed in order to meet your specifications.

With the "resample image" box checked and a size of 8×6 chosen and 128 dpi used, no resampling will be done as the original image will meet those specs. But if you now pick 16×12 as your desired image size at 128 dpi, there are not enough pixels to meet that goal.

So Photoshop will generate new pixels using the method chosen in the little choice box next to the "resample image" box. In this case your new image will have 2048 pixels across and 1536 pixels across (and your image will be four times its original size) but at most 25% of the pixels will be your original ones.

The resulting image may well be fine for your purposes.

If you downsize the image by specifying a dpi and a size, Photoshop will comply by generating an image from yours
with the needed pixels. It is likely that all the pixels in the new image will have been calculated by Photoshop.

So the idea is simple. It is the "resample image" box that controls how the image is resized. With it unchecked the image is UNCHANGED and Photoshop just shows you how
many dpi you’d get at the requested size or what the size would be at the requested dpi.

With it checked Photoshop will honor your requested dpi and dimensions and adjust the number of pixels to meet that.

Does that help?

—- Paul J. Gans
V
Vincent
Apr 26, 2004
Does that help?

well, it helped me.
Thnx
W
wnor
Apr 26, 2004
Steve, here is my take on this. If you are sizing for print (which I assume you are), then 300 dpi is the usual one to choose. If you have resampling turned on, then the image will be upsampled (pixels added) and therefore not sharp. If you choose 330 dpi with resampling turned off, then the image will get smaller.
You should shoot your images at as high a resolution as possible, then you can resample down, which doesn’t degrade the image as much. What size image are you starting out with?

"steve" …
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes the image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

–Some Good People–
www.saHOSTplus.com
Full cPanel hosting starting $2.95 a month
Use this coupon (Group 50% OFF) and receive 50%
off from all hosting and reseller hosting packages
offer expire on 2004/05/01
S
steve
Apr 26, 2004
I’m Starting with 215mm x 216mm resolution 300dpi
but I have not scan it or import the image, I’m just creating a new image

Yes the image is for printing

Steve, here is my take on this. If you are sizing for print (which I assume you are), then 300 dpi is the usual one to choose. If you
have
resampling turned on, then the image will be upsampled (pixels
added)
and therefore not sharp. If you choose 330 dpi with resampling
turned
off, then the image will get smaller.
You should shoot your images at as high a resolution as possible,
then
you can resample down, which doesn’t degrade the image as much. What size image are you starting out with?

"steve" wrote in message
news:<c6j979$gbv$>…
Hi all
I have always have a problem understanding that, can someone
please
explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm
and
300dpi
but if I change the Resolution for example to 50dpi that changes
the
image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

–Some Good People–
www.saHOSTplus.com
Full cPanel hosting starting $2.95 a month
Use this coupon (Group 50% OFF) and receive 50%
off from all hosting and reseller hosting packages
offer expire on 2004/05/01
S
steve
Apr 27, 2004
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm
and
300dpi
but if I change the Resolution for example to 50dpi that changes
the
image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

Perhaps it will help if I take a shot at explaining what is going on here.

Your original image contains a certain number of pixels across and a certain number down. That’s all that you image has. It knows nothing about size.

For the sake of argument let us assume that you have an image that is 1024 pixels across and 768 down.

If you tell Photoshop that you want this image to be at 256 dpi *AND* if you have the "resample image" box unchecked, it will tell you that the image is 4.00 inches across and 3.00 inches down.

If you tell Photoshop that you want this image to be at 128 dpi *AND* if you have the "resample image" box unchecked, it will tell you that your image is 8.00 inches across and 6.00 inches down.

In neither case has the number of pixels changed.

Alternatively you could set the dimensions and see what dpi you would get.

On the other hand, if you check the "resample image" box, Photoshop will attempt to add or subtract pixels as needed in order to meet your specifications.

With the "resample image" box checked and a size of 8×6 chosen and 128 dpi used, no resampling will be done as the original image will meet those specs. But if you now pick 16×12 as your desired image size at 128 dpi, there are not enough pixels to meet that goal.

So Photoshop will generate new pixels using the method chosen in the little choice box next to the "resample image" box. In this case your new image will have 2048 pixels across and 1536 pixels across (and your image will be four times its original size) but at most 25% of the pixels will be your original ones.

The resulting image may well be fine for your purposes.

If you downsize the image by specifying a dpi and a size, Photoshop will comply by generating an image from yours
with the needed pixels. It is likely that all the pixels in the new image will have been calculated by Photoshop.
So the idea is simple. It is the "resample image" box that controls how the image is resized. With it unchecked the image is UNCHANGED and Photoshop just shows you how
many dpi you’d get at the requested size or what the size would be at the requested dpi.

With it checked Photoshop will honor your requested dpi and dimensions and adjust the number of pixels to meet that.
Does that help?

—- Paul J. Gans

Still busy trying to figer out how do I setup the image so it appear the same size as it will be after it is printed
PJ
Paul J Gans
Apr 27, 2004
Vincent wrote:
Does that help?

well, it helped me.
Thnx

You are welcome.

—- Paul J. Gans
PJ
Paul J Gans
Apr 27, 2004
steve wrote:
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm
and
300dpi
but if I change the Resolution for example to 50dpi that changes
the
image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

Perhaps it will help if I take a shot at explaining what is going on here.

Your original image contains a certain number of pixels across and a certain number down. That’s all that you image has. It knows nothing about size.

For the sake of argument let us assume that you have an image that is 1024 pixels across and 768 down.

If you tell Photoshop that you want this image to be at 256 dpi *AND* if you have the "resample image" box unchecked, it will tell you that the image is 4.00 inches across and 3.00 inches down.

If you tell Photoshop that you want this image to be at 128 dpi *AND* if you have the "resample image" box unchecked, it will tell you that your image is 8.00 inches across and 6.00 inches down.

In neither case has the number of pixels changed.

Alternatively you could set the dimensions and see what dpi you would get.

On the other hand, if you check the "resample image" box, Photoshop will attempt to add or subtract pixels as needed in order to meet your specifications.

With the "resample image" box checked and a size of 8×6 chosen and 128 dpi used, no resampling will be done as the original image will meet those specs. But if you now pick 16×12 as your desired image size at 128 dpi, there are not enough pixels to meet that goal.

So Photoshop will generate new pixels using the method chosen in the little choice box next to the "resample image" box. In this case your new image will have 2048 pixels across and 1536 pixels across (and your image will be four times its original size) but at most 25% of the pixels will be your original ones.

The resulting image may well be fine for your purposes.

If you downsize the image by specifying a dpi and a size, Photoshop will comply by generating an image from yours
with the needed pixels. It is likely that all the pixels in the new image will have been calculated by Photoshop.
So the idea is simple. It is the "resample image" box that controls how the image is resized. With it unchecked the image is UNCHANGED and Photoshop just shows you how
many dpi you’d get at the requested size or what the size would be at the requested dpi.

With it checked Photoshop will honor your requested dpi and dimensions and adjust the number of pixels to meet that.
Does that help?

—- Paul J. Gans

Still busy trying to figer out how do I setup the image so it appear the same size as it will be after it is printed

What is the pixel size of the image. That’s what counts, not the size in inches or millimeters or whatever.

I assume that you are printing the image at 300 dpi. If your desired image size is 215×260 mm, that’s about 8.5 x 10 inches.

(You will be a much happier camper if you work in metric *OR* in English. Don’t mix them unless you are very careful. 300 dpi is essentially 120 dots per cm or 12 per millimeter, but you likely know that.)

Calculate how many pixels you will need for the image. It works out to be 2550 x 3000. If you have that many, you are in good shape.

If you have more, you will have to downsample. To do this check the "resample image" box, set the dpi to 300 and the size to 8.5×10. Photoshop will give you the new pixel
size of the image, which should be the numbers above unless I’ve made a mistake in the math. Then click OK and the picture will be resampled to the desired size. It should be fairly sharp, but you might want to sharpen it.

If you have fewer pixels you will have to upsample. Do
*exactly* the same thing, but now your image will very
likely be less sharp. If this is true, sharpen it before printing.

That’s all there is to it.

Two comments though. The first is SAVE YOUR IMAGE before manipulating it. The second is try to understand what is going on. It will help you in many other situations.

—- Paul J. Gans
G
Getho
Apr 27, 2004
have a look at this…
http://www.ediblemedia.com.au/client-tutorials.html
hope it helps
Geth

"steve" wrote in message
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes the image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

–Some Good People–
www.saHOSTplus.com
Full cPanel hosting starting $2.95 a month
Use this coupon (Group 50% OFF) and receive 50%
off from all hosting and reseller hosting packages
offer expire on 2004/05/01

S
steve
Apr 27, 2004
Hi all
I have always have a problem understanding that, can someone please explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm and 300dpi
but if I change the Resolution for example to 50dpi that changes
the
image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

Lets see if I have it right

1. I start new image size 216mm x 260mm and 72dpi
2. then edit the image
3. resample the image to 300dpi whit resample image tarn off
4. print image
I will get a bed quality
so this is the WRONG WAY

1. I start new image size 215mm x 260mm and 300dpi
2. edit the image
3. print the image
this will bee a good quality
so this is the CORRECT way

is that right

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Full cPanel hosting starting $2.95 a month
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J
jaSPAMc
Apr 27, 2004
If it’s a created image, then start with the ‘dimensions’ and dpi you want for printing. You’ll probably never see it ‘life size’ on the monitor, but you can approximate by enlarging/reducing the window you use.

CTRL + ALT + "+/-" to get close.

On Tue, 27 Apr 2004 01:43:36 +0200, "steve"
found these unused words floating about:

I’m Starting with 215mm x 216mm resolution 300dpi
but I have not scan it or import the image, I’m just creating a new image

Yes the image is for printing

Steve, here is my take on this. If you are sizing for print (which I assume you are), then 300 dpi is the usual one to choose. If you
have
resampling turned on, then the image will be upsampled (pixels
added)
and therefore not sharp. If you choose 330 dpi with resampling
turned
off, then the image will get smaller.
You should shoot your images at as high a resolution as possible,
then
you can resample down, which doesn’t degrade the image as much. What size image are you starting out with?

"steve" wrote in message
news:<c6j979$gbv$>…
Hi all
I have always have a problem understanding that, can someone
please
explain it to me.
I need to make image size (similar too A4 format) 215mm x 260mm
and
300dpi
but if I change the Resolution for example to 50dpi that changes
the
image size to
and if I go with 300dpi it look like it is too big for A4 size Can some one please give me a quick lesson
Thanks

–Some Good People–
www.saHOSTplus.com
Full cPanel hosting starting $2.95 a month
Use this coupon (Group 50% OFF) and receive 50%
off from all hosting and reseller hosting packages
offer expire on 2004/05/01
S
steve
Apr 30, 2004
Now that image look to big and if I fill it in with information then how it is going to fit to be printed in a 215mm x260mm

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offer expire on 2004/05/01
S
steve
Apr 30, 2004
Now that image look to big and if I fill it in with information then how it is going to fit to be printed in a 215mm x260mm

Now the printing people say the text is to small.

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