Saving .JPG with same quality as I opened it. Harder than you'd think!

idrinkpago · #1 06-06-2007, 04:16 PM

I open a .JPG with GIMP. Then I choose Save As. I get an option what quality I want to use. I choose 100%. Still the new .JPG has lower quality than the original image. Do you know of any way I can keep the original quality?

EDIT: The colors become all different and it looks like [censored]

kerowo · #2 06-06-2007, 04:36 PM

The jpg format uses a lossy compression algorythm, which means every time you save it you loose quality. In the photographic world jpgs are the last format you use before printing or sending it out, not what you use for editing. That is usually .tiff, the RAW file from the camera, or an internal photoshop format.

castlevania · #3 06-06-2007, 04:44 PM

[ QUOTE ]
The jpg format uses a lossy compression algorythm, which means every time you save it you loose quality. In the photographic world jpgs are the last format you use before printing or sending it out, not what you use for editing. That is usually .tiff, the RAW file from the camera, or an internal photoshop format.

[/ QUOTE ]

Thanks kerowo! Does that mean there is no way? Or can I save it as lossless .JPG some way to retain the quality?

kerowo · #4 06-06-2007, 04:49 PM

If you are staring with a jpg I'm not sure of a way around it. You might try converting it to a different format and working with that format in your photo editor.

Beavis68 · #5 06-06-2007, 06:13 PM

save the file as a TIFF and do any work you need to do to it as a TIFF. Then you can save it is a JPEG when you are done if you need to compress it.

Why are you saving it again anyway?

LuckyTxGuy · #6 06-06-2007, 06:36 PM

Ok wait....you are opening up a nice looking .jpg, editing it or whatever, then saving in the highest possible setting and it looks noticeably worse than the original? Something is wrong, that is not how it is supposed to work.

I know basically nothing about Gimp other than having seen it a few times but photography is one of my main hobbies and I edit photos in Photoshop almost daily. I've read alot of articles on this and while editing .jpgs and saving them multiple times is not recommended, the human eye will rarely, if ever, be able to see any deterioration at a normal viewing resolution if the .jpg is saved each time in a high quality level.

I say all that to say, something ain't right.lol You should not be able to notice any change in the .jpg, especially something like the colors becoming screwed up etc.

Do you have any other editing software? Why not open up one of these nice looking new .jpgs in something as simple as Paint then saving it as a .jpg and see if the problem happens there. I'm really thinking this is some sort of Gimp error.

Can you post a example of one of these images that is messed up after saving?

kerowo · #7 06-06-2007, 08:24 PM

I've noticed it when making a lolcat caption, but that was starting with a pretty low res jpg to begin with, he could also be using crappy image editing program as well.

idrinkpago · #8 06-06-2007, 08:37 PM

I later saw that there were advanced options you could change as well. One of the advanced options was subsamplig. When I chose 1x1,1x1,1x1 the quality became much better. Now I don't deem to be able to see a difference between the original and the copy. When I use the tools in GIMP I can detect that the images are still different but I am very content as it is now. Everything looks nice!

Other advanced options are optimize (prechecked), progressive, force basic JPEG (prechecked), Save EXIF-data (prechecked), DCT-method (Whole number). I don't know if any of those can increase the quality even further.

kerowo · #9 06-06-2007, 08:43 PM

Exif data is the camera settings used when the picture was taken, so it doesn't do anything for image quality.

LuckyTxGuy · #10 06-06-2007, 10:33 PM

Sorry I'm just not familiar with Gimp, however, I know that it is a very popular free program. Sounds like you might have solved it though....

But like I said, you shouldn't be able to notice any deterioration by just saving the file once or twice as a .jpg. I edit all my photos, usually saving them as .psd (Photoshop format) at time because it is lossless but also preserves any layers that I've created. However, I always save the final edited photo as a .jpg again for commercial printing.

Hope you've got it working!