PNG file format vs JPG

LO
Posted By
Lee_Olson
May 14, 2005
Views
481
Replies
12
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Closed
Someone on another board has suggested saving images in PNG vs JPEG format as there is no loss of information like you get when saving a JPEG image. Photoshops PSD saves all information also but creates very large files and is not viewable unless you open PS.

Does anyone have any input on PNG file formats. If I am not going to use my images professionally ( I will be just making prints for myself) is saving in PNG a good idea? I really liked the fact that you can edit and save many times without photo degradation.

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DM
dave_milbut
May 14, 2005
mozilla/firefox opens png. rumor has it the IE7 will also (finally!) fully support png.
C
Corey
May 14, 2005
Currently, IE supports PNG format in a limited fashion. It will display a PNG but not it’s transparency.

As for the OP’s original question, I prefer to save as a layered PSD for editing. Resaving as a JPG will cause degradation if resaved from the original PSD and overwriting the previous version of the JPG. A JPG will usually be smaller in file size than a PNG. This matters only on the Web. The PNG won’t have the artifacts associated with JPG compression.

Peadge 🙂

wrote in message
mozilla/firefox opens png. rumor has it the IE7 will also (finally!) fully
support png.
Y
YrbkMgr
May 14, 2005
PNG is a format that uses lossless compression. It should replace JPG, but since, as Dave mentioned, IE doesn’t support all the features of PNG, not many people use it. But IE WILL display PNG formats, just not all of the features of PNG.

PNG supports transparency, JPG does not. But IE will not support the PNG transparency. PNG on the other hand, while using lossless compression, it doesn’t really achieve the file sizes that JPG can.

Most of the issues related to PNG v. JPG have to do with web.

Based on your questions, PNG is a decent choice for personal use. However, not many people who have worked with images for any length of time would choose that format. It is more common to save your files as TIF, since tiff supports transparency AND layers, AND uses lossless compression.

There are a lot of folk who want to keep their file size down – for the web it makes sense, but you’ll find that most people who do a lot of image editing know that they’d rather have great data than compromise on disk space. In fact, many people keep a copy of the raw, uneditied original, and make their edits on a copy of the image. I point this out so as to suggest that disk space is less important than image quality, and the price of image quality is file size, in general.

Peace,
Tony
C
Corey
May 14, 2005
OOOOPS! Change the second sentence below to: Resaving as a JPG will NOT cause degradation if resaved from the original PSD and overwriting the previous version of the JPG.

Peadge :-\

"Peadge" wrote in message
Currently, IE supports PNG format in a limited fashion. It will display a PNG but not it’s transparency.

As for the OP’s original question, I prefer to save as a layered PSD for editing. Resaving as a JPG will cause degradation if resaved from the original PSD and overwriting the previous version of the JPG. A JPG will usually be smaller in file size than a PNG. This matters only on the Web. The PNG won’t have the artifacts associated with JPG compression.
Peadge 🙂

wrote in message
mozilla/firefox opens png. rumor has it the IE7 will also (finally!)
fully
support png.

TM
Trevor_Morris
May 14, 2005
Tony has summed it up quite well, but if you still have a few questions, here is an article/tutorial that explains that features and benefits of PNG. It also discusses Photoshop’s support for PNG as well as that of common browsers.

The PNG File Format
<http://user.fundy.net/morris/photoshop26.shtml>
R
RSD99
May 14, 2005
"Lee_Olson" posted:
"…
Photoshops PSD saves all information also but creates very large files and is not viewable unless you open PS.
…."

FWIW:
I can view PhotoShop (PSD) files quite nicely using IrfanView … http://www.irfanview.com/main_start_engl.htm

wrote in message
Someone on another board has suggested saving images in PNG vs JPEG
format as there is no loss of information like you get when saving a JPEG image. Photoshops PSD saves all information also but creates very large files and is not viewable unless you open PS.
Does anyone have any input on PNG file formats. If I am not going to use
my images professionally ( I will be just making prints for myself) is saving in PNG a good idea? I really liked the fact that you can edit and save many times without photo degradation.
DM
dave_milbut
May 15, 2005
png was originally created as a replacement for gif when the patent holders decided to enforce their patant AFTER gif had already become ubiquitous on the web/intenet.
DM
Don_McCahill
May 15, 2005
Actually, there never was a patent on GIF. It was created by Compuserver users for graphic interchange. Unfortunately, they used a compression technique that was patented. The original patent holder did not complain since it was a non-profit use.

However the company holding the patent was sold, and the new owner announced that it would enforce its patent rights and demanded royalties. In the initial scare that provide the impetus for PNG development (by many of the same folks that made GIF) people thought this meant that web designers and others using GIF images would be forced to pay.

It turned out that the new owners were not quite that evil. They only wanted money from programs that created GIFs. This includes Adobe, which still pays a royalty for the use of GIF. Most shareware graphic programs do not support GIF because of the fee.

Thinking about it, there is no way that a web designer could be made to pay a royalty, since possession or posting a GIF does not make use of the compression patent. Only the creation of the GIF uses that code, so that is the limit of the legal reach.

I think the company involved is Honeywell, now Honeywell-Bull, but I might be off on that.

(End of Internet History Lesson)

Don McCahill
MD
Michael_D_Sullivan
May 15, 2005
I seriously doubt Adobe still pays that royalty, since the LZW patent expired in 2004.
DM
dave_milbut
May 15, 2005
This includes Adobe, which still pays a royalty for the use of GIF.

what mike said. and it was unisis. otherwise, nice writeup don.

gif patant. dead at 20. 🙂
<http://www.kuro5hin.org/story/2003/6/19/35919/4079>
DM
Don_McCahill
May 15, 2005
Thanks for that Mike. I didn’t realize the patent expired. (I thought they lasted longer than that … must be thinking of copyright too much).
R
RSD99
May 15, 2005
IIRC … everything you posted is correct, except that the "Company" was Unisys.

wrote in message
Actually, there never was a patent on GIF. It was created by Compuserver
users for graphic interchange. Unfortunately, they used a compression technique that was patented. The original patent holder did not complain since it was a non-profit use.
However the company holding the patent was sold, and the new owner
announced that it would enforce its patent rights and demanded royalties. In the initial scare that provide the impetus for PNG development (by many of the same folks that made GIF) people thought this meant that web designers and others using GIF images would be forced to pay.
It turned out that the new owners were not quite that evil. They only
wanted money from programs that created GIFs. This includes Adobe, which still pays a royalty for the use of GIF. Most shareware graphic programs do not support GIF because of the fee.
Thinking about it, there is no way that a web designer could be made to
pay a royalty, since possession or posting a GIF does not make use of the compression patent. Only the creation of the GIF uses that code, so that is the limit of the legal reach.
I think the company involved is Honeywell, now Honeywell-Bull, but I
might be off on that.
(End of Internet History Lesson)

Don McCahill

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