LarryFitz Loc: Beacon NY

classic320

This has been one of the most informative threads I've experienced on this site. Thanks!

kkdji1

I have not ventured into the world of PP outside of what I do in the PHotos editing program on my Mac laptop. I have only shot in Raw a few times. When I imported the files into Photo I wasn’t sure how to convert it to a jpeg or if I could even PP the raw file in Photos. Do you know if Photos can PP raw files? I am going to New Zealand tomorrow and am hoping to capture some great landscape photos and would love to shoot in both raw and jpeg.

EdU239 Loc: The Northeast

Am I correct in concluding that the size of the file, say 2 MB for a jpg from my G16, would go down over time? If so, what is the rate of loss per Save? Or does this vary depending on the software being used?

Rich1939 Loc: Pike County Penna.

Ha! Here on UHH 'Posting' = opening Pandora's box
sorry, sometimes I can't help myself

dsmeltz Loc: Philadelphia

Which "Manual of Photography" are you reading? There are a number of books claiming that title.

jcboy3

It's really not that simple. It is possible to do many different types of edit to a JPG file without degrading the image. There are lossless JPG editors available that perform many edit functions in a lossless manner. They do have to be written for it, so you need to be aware of what you are doing and what application you are using. Yes, the general photo editing applications do not support lossless JPG editing (yet), but that is not a characteristic of the JPG format.

See for example:

https://www.betterjpeg.com

dcampbell52 Loc: Clearwater Fl

Agreed!!, If I shoot jpg at all (and I only do it in certain situations), I will shoot RAW+Jpg. Its just that simple. Then I have a jpg immediately, for the person that wanted it. And, I can take a few minutes and process the RAW and make a much better presentation. People seem to forget that ANY editing, which includes cropping, will result in saving (thus degradation) of the photo. Yes, it may take 10 or more edits to be visual but they are there and not representative of my work.

camerapapi Loc: Miami, Fl.

Bob,we perfectly know that a JPEG file suffers some image degradation every time it is saved and we also understand the fact that it is a lossy file. As you very well know compression has a lot to do with the degradation of the image and the general recommendation is to work always with a copy leaving the original alone and to use a low compression when saving the original to preserve details. I like to save a good JPEG file as a TIFF knowing that the data will be properly preserved. I do not find labs in my area that print from TIFF files.

Although JPEG images degrade quality when saving it is not that easy to see the degradation. I do see in many of them that some sharpness is lost but it takes many saves to actually degrade the image to the point of making it useless. JPEG images are the universal file and if we start with RAW sooner or later we will have to convert to a JPEG and to a certain extent we will loose data from that RAW file. It does not matter if we processed the RAW image using Adobe RGB or ProPhoto, we are going to loose colors as we compress the file to sRGB. I have said several times in the forums that it is impossible to judge quality based on a file that has been compressed for Internet use. If anyone wants to see quality it is mandatory to look at the original.

Modern JPEG files are not the same JPEG files of 10 years ago. Manipulating those files were a nightmare at the time but modern JPEGs are of excellent quality and I use those files often with my photography at low compression to make sure I get the best quality possible. Olympus uses super fine compression with their JPEG files and the quality is excellent.

I do not want you or anybody else to misunderstand me, I am not saying JPEG is better than RAW. A RAW file has all the original data because there has been no intervention by the firmware of the camera but once we begin to convert to JPEG that original RAW file will degrade in quality, beginning with making a 12 bits image into an 8 bits one. Color degradation I already talked about when making the conversion from a wide gamut to a smaller one like it is the sRGB color space. How many millions of colors we can see I do not really know.

What I am saying is that we started with a file that had all kind of details and colors and part of them will be lost when we convert to a JPEG file even when our eyes in the majority of the cases will not notice the changes.
I find important to notice that invariably changes will take place every time a JPEG file is saved and that the best way to preserve quality is to keep the RAW image or to convert the original file to TIFF for future use. Working during editing in a non destructive way is also important to keep quality.

I use both files to my satisfaction and with care JPEG images can yield excellent quality. These are the facts I know.

bweber Loc: Newton, MA

I shoot raw on one card and JPEG on my second card, and usually ignore the jpeg and process the raw image. However there is a very simple solution to the problem of saving JPEGs that degrade. Use your software to create a duplicate JPEG and post process the duplicate. You can always return to the original and start over if you feel that you lost to much detail in post processing.

rborud Loc: Minnesota

Thanks Bob this is very clear and concise. RBorud

DaveC1 Loc: South East US

If I understand your question the answer is no. What your doing is file transfer. You are not opening the file in a program and then saving the file. You can transfer files, make multiple copies of .jpg files, even archive files to the cloud or an external hard drive without ever opening that file. As long as the file is not corrupted its still exactly the same file, and if the file were corrupted it probably would not be readable anyway.

srt101fan

I thought your original post was very clear, concise and helpful. It still is, despite the attempts by some to muddy the waters.

Mr palmer Loc: Currently: Colorado, USA, Terra, Sol

This is true, but I would point out that by using the term "degradation" repeatedly, you are scaring a lot of people away from doing their own work. Who wants to "degrade" their images?
Perhaps you could include some suggestion for doing the experiment yourself. Something like 1) shoot a detailed jpg image, 2) open and save it 10 times under different names, 3) pull the original and the final up and view them at 100% to see the differences.
This method may result in some surprises, but giving people the tools for individual investigation of truth is generally more in keeping with the spirit of the age we live in.

Walt

John_F Loc: Minneapolis, MN

There is a Wikipedia article entitled "Joint Photographic Experts Group" that tells about the various jpeg versions. It is written in 'techno-speak' and not for the faint hearted. One remark that one version is 60% less lossy than the original.