Info from Adobe: For example, if you crop then export as tiff, you'll lose the border. Likewise, if you move the black-point way in, then export as tiff, you'll lose the blacks, permanently. Ditto for the whites..

Bottom line: tiffs are not lossily compressed, so there is no loss due to compression (as there is with jpeg), but exporting and re-importing can result in loss, which is why Lightroom uses a non-destructive workflow where original stays original, and you are always exporting the original, with edits applied to it, instead of exporting an export, with edits applied to it...

I PROVED that, for practical purposes, and for those who extensively use JPGS, degradation should not be a problem when opening and saving. My exercises in opening and saving and closing over and over up to ten times PROVED this, and the reults were published here for all to see. That is what I set out to do in this topic and I cannot see that I failed. However, I still advocate converting to TIFF, regardless of file size.

Info from Adobe: For example, if you crop then export as tiff, you'll lose the border. Likewise, if you move the black-point way in, then export as tiff, you'll lose the blacks, permanently. Ditto for the whites..

Bottom line: tiffs are not lossily compressed, so there is no loss due to compression (as there is with jpeg), but exporting and re-importing can result in loss, which is why Lightroom uses a non-destructive workflow where original stays original, and you are always exporting the original, with edits applied to it, instead of exporting an export, with edits applied to it...

I PROVED that, for practical purposes, and for those who extensively use JPGS, degradation should not be a problem when opening and saving. My exercises in opening and saving and closing over and over up to ten times PROVED this, and the reults were published here for all to see. That is what I set out to do in this topic and I cannot see that I failed. However, I still advocate converting to TIFF, regardless of file size.

To all interested posters.
My topic was to demonstrate that it is possible to open and save a JPG, whether or not in a viewer or editor, wthout degrading.
However, I have here chosen a photo (JPG) and, using XnView, have opened and "saved as" ten times. The first "save as" (P1687a1) and the tenth "save as" (P1687a10) are attached herewith - both files are 1.62 mb. I have compared them side-by side at 100% using PhotoFiltre. I see no degradation. BTW - the pic was chosen, not for it's quality, but because it is good for the demo.

Let's not confuse the question of (a) opening, saving and closing with (B) opening, editing saving and closing. It's pretty clear that editing (b) an 8-bit file is likely to cause degradation.

It's also clear that (a) simply opening and saving a JPEG once is unlikely to produce any visible degradation unless the quality is deliberately reduced from 100% or whatever the editor considers the best quality JPEG compression.

Evidence of degradation was offered in Saving JPEG Photos Hundreds of Times which required 500 open/save/close cycles. That is going to ridiculous extremes to prove a point - a bit far-fetched.

What Delderby has suggested is that a mere 10 cycles of open/save/close (no editing) does not produce any visible degradation, at least not any that you can detect without severe pixel peeping.

You might think that Delderby had somehow committed unforgivable heresy and offended every post processing purist.

There is no reason to get up-tight about the notion that invisible damage is simply irrelevant. A photograph is, after all, a visible phenomenon.

Pixel peeping and splitting hairs over numbers may be an opportunity to display one's knowledge. It does not make anyone a better photographer.

You say that you have "slight problems". From your posts in this topic it seems that you have big problems - certainly in comprehending the written word, and in your negativity.
I PROVED that, for practical purposes, and for those who extensively use JPGS, degradation should not be a problem when opening and saving. My exercises in opening and saving and closing over and over up to ten times PROVED this, and the reults were published here for all to see. That is what I set out to do in this topic and I cannot see that I failed. However, I still advocate converting to TIFF, regardless of file size.

How many times have you looked at yourself in the mirror and thought, "That's a degraded version of what I was yesterday." How often have you posted a JPEG with the excuse, "Sorry, that's just a degraded version of what I was looking at before I saved it."

I'll bet never. So we are not arguing about absolute degradation, which is inevitable. It's a question of incremental degradation and whether it is visible.

Compared to the scene you captured with your camera, an image is no more that a degraded version of reality. Everything you do to it will either enhance it or degrade it.

The degradation that occurs from a single save of a JPEG (or four or ten) is simply not worth arguing about. If you think there is enough degradation to matter, don't do it.

There has been discussion here in the last two days, with the consensus of opinion being as follows:
If you save a JPG after opening and editing, it will be degraded because it is a lossy format.
That it will deteriorate rapidly the more times you repeat the above step.
That you cannot save without changing something, as the "save" tab will be greyed out.
Some said merely opening and closing will degrade the JPG.

My favourite viewer is XnView. It is a viewing and file management program that has some basic editing facilities and is free to a good home.
In XnView it is possible to open and then save a JPG without any editing or changing of the file. The prog first asks "The file already exists - do you want to overwrite it"?
Using Xnview, I opened a JPG file, saved and closed, then repeated the process 20 times. the pixel size was 3056x4584. After the opening, saving and closing session, the file size had not altered, remaining at 3056x4584. I examined the file at 100% and found no evidence of degradation.
I am aware that you cannot do this with any prog, but you can with XnView.