Resize Jpeg would this work?

I have been readinng that each time a JPEG is edited and saved saved it downgrades a little. As I have lots of JPEGs or JPGs I wonder if this will work.

Open the JPG in a photo editor say Elements 12 or Affinity.

Edit the picture

Save the result in some other format e.g. TIF or PNG etc.

If my understanding is correct the JPG type picture is now saved as a sort of PNG or whatever 'copy' that I can open and edit it to my hearts content and the picture will not be compressed every time I save it unless I save it as a JPEG type..

So the PNG will not degrade any further, the JPG compression will not be put back to a higher level but I will at least have a picture I can work on way into the future and provided I continue to save it as something other than a JPG there will no longer deteriorate.

So in essence whilst my picture will never return to level 12 JPG, provided I save it as some other format it won't get worse.

Is that right or have I completely misunderstood what happens?

Ron

The real question is What difference exists (if any at all) between the process which is proposed in OP, vs. simply storing JPG with no compression at all ( lossless (100% quality) image), when multiple Saves with subsequent re-edit are envisioned?"

It is supposedly a fact that even at 100%, there is some new compression being done every time. I've never seen it, and certainly using PS the file size doesn't seem to get smaller. maybe I don;t save enough times to see it.

I won't dispute the validity of the claim, but will point you to first, some facts vs. falsehoods that are often repeated;
https://www.lifewire.c​om/jpeg-myths-and-facts-1701548

And to this where someone tried to see the diminished quality, and after 30 re-saves, failed to find any evidence of such loss in quality;
https://improvephotogr​aphy.com …mes-reduce-image-quality/

CyberDyneSystems wrote in post #18960258
It is supposedly a fact that even at 100%, there is some new compression being done every time. I've never seen it, and certainly using PS the file size doesn't seem to get smaller. maybe I don;t save enough times to see it.

I won't dispute the validity of the claim, but will point you to first, some facts vs. falsehoods that are often repeated;
https://www.lifewire.c​om/jpeg-myths-and-facts-1701548

And to this where someone tried to see the diminished quality, and after 30 re-saves, failed to find any evidence of such loss in quality;
https://improvephotogr​aphy.com …mes-reduce-image-quality/

Curious, I just opened an image using Paint Shop Pro 2020, saved it as Gen1 with highest JPG quality, closed it, re-opened Gen 1 and saved it as Gen 2 with highest JPG quality, and did that thru Gen10. Then, using a web image comparison tool, I compared Gen1 vs. Gen10 and viewed the Difference display...absolutely blank (no differences found at all). Better than a subjective eyeballing to detect differences between two images, this program did a digital comparison bit by bit for any differences at all.
I figured it was the true obsessive-compulsive photographer who would re-open and re-save a file more than 10 times, so based upon my own testing I am satisfied enought that 'highest quality' (at least while using Paint Shop Pro 2020) means 'no deterioration' even after 10 generations of 'virtually same' quality.

[edit: I just did this comparison as a control test...saved Gen11 as a highest compression JPG, compared Gen11 vs Gen1 differences in red:]

Canon has a good write up on this topic at https://cpn.canon-europe.com …_and_lossy_comp​ression.do.

On this topic, and admittedly about 15 years ago, I went to a 2-day photo school put on by a well known camera manufacturer (not Canon). I remember a demo of a image taken of a quarter with a macro lens. After many saves, perhaps as many as 25 to 30, the detail on the coin was gone. It essentially looked simply like a somewhat out of focus disk. OK, maybe the intelligent person would not do a save with 25 repetitions, but the point was to simply demo what compression could do to an image.

If you have concerns, it is probably best you understand the RAW format, and save in both RAW +JPG. RAW is discussed very simply in the link I provided above.

John from PA wrote in post #18960276
Canon has a good write up on this topic at https://cpn.canon-europe.com …_and_lossy_comp​ression.do.

The OP should keep in mind that John's link discusses the topic of JPG compression as implemented by Canon within the Canon camera itself.
Completely separate is how any specific postprocessing software deals with JPG compression...some use a grade 1 - 12, others use percentage 0 - 100%, as one simple example that JPG compression is not uniformly dealt with in software!

My 10 generation Open/Save test might have resulted differently, even using the highest JPG quality (lowest compression) in a different application program.

Wilt wrote in post #18960286
The OP should keep in mind that John's link discusses the topic of JPG compression as implemented by Canon within the Canon camera itself.

True, there is only a small amount of discussion of the degradation effects external to the camera when processing. More discussion, again somewhat “general” in nature but more toward the degradation of external processing can be found at https://collab.its.vir​ginia.edu …0Image%20Degrad​ation.html

Reviving this topic, a timely article at https://fstoppers.com …uality-degradation-435235

Thanks to all who offered advice. greatly appreciated. Ron

That was one of the first things things they taught us when I took a PS class in 2006, give or take a year. Jpeg is a lossy format. Like stated to what end? Will anyone really notice it? Being a purist and trying to squeeze as much detail as I can especially for bird/wildlife shots I edit in CR2/3 or TIFF because in the back of my mind something is taking a hit editing with Jpegs.