Ysarex Loc: St. Louis

OK -- got the groceries.

Here's an example of what you wanted to see. I selected an image from an older 12 megapixel camera so we can see this in this venue. As I mentioned just above, this is becoming less and less an issue as we increase the resolution of our cameras. What happens still happens but most folks use the photos in ways in which the damage isn't visible.

First there's an illustration below with three images so you can see what degree of editing was done. The more editing the more extreme the damage. This is pretty mild. I processed the raw file, I had the SOOC JPEG from the camera and the final image is created by editing the SOOC JPEG. The camera created an image too flat, too light in the sky and overall shifted cyan.

The next illustration below shows a side by side chunk of sky at 100% of those three images. The SOOC JPEG has a slight molted look at 100% -- little noise -- but it's not bad and viewed at less than 100% it looks fine. It needs to be noted here that the camera software applied some overall sharpening and that's having an impact in what you see in the SOOC JPEG. In processing the raw file I did not sharpen the sky.

You can see the edited JPEG looks worse. What you're seeing in that case is the original JPEG compression grid embedded in the image that was pretty well hidden in the SOOC original now interacting with the edit changes. You've got these grid cells and they're part of the image now. They have congruent sections of pixels that are all the same created that way by the JPEG algorithm. As we apply edit changes to tone/color it's almost like spraying a hose on a sand filled grid of rebar, we expose the grid.

The third illustration is a 200% view of a piece of sky from the edited JPEG. I circled a spot where you can actually see two grid cell corners together. If you look over that chunk of sky you can start to see more and more solid bars and corners that are part of grid cells. This is uniquely a JPEG "thing" and it's different than the issue of recompressing a JPEG or editing an 8 bit image (those are additional problems). Worth noting that converting a JPEG to TIFF before editing has no effect on this issue since that embedded compression grid is unchanged in the converted TIFF. You'll be able to avoid recompression damage.

(Download)


(Download)

btbg

First, even when necessary cropping degrades image quality, so given a choice of using a bigger lens or cropping usually using a bigger lens is the way to go.

Second some cropping will happen when you print unless you chose a format to print in that is full frame. For example, an 8x12 rather than an 8x10. If you are commonly printing images in sizes like 8x10, then you need to make sure you leave enough space to crop.

I can't speak for Ron, but what I think he is saying is that people rely too much on cropping to fix images. They crop to straighten the horizon, when they should get that straight in the camera. They crop because there is a cigarette butt in the foreground (that actually happened in our wedding photos even though neither of us smokes. The photographer didn't notice and now, 40 years later we still have them in our wedding photos.)
They crop because there is a distracting branch in one corner. They crop because they discovered that their composition was not as strong as they thought it was and cropping "improves" the image. In each of those and countless other examples addressing the problem before shooting would have made cropping unnecessary.

Ysarex Loc: St. Louis

But it's there. That's all I've said. When a JPEG is created a grid of typically 8x8 pixels is laid over the image and used to create redundancy in the image. That compression grid -- those compressed grid cells -- are incorporated and saved as part of the image. When the image is edited and changes of tone/color are made those changes interact with those embedded grid cells and bad things happen as a result. Those bad things are different than what happens if a JPEG is recompressed and different than what happens if an 8 bit image is edited.

That's all I've said and it's correct -- see my most recent response to JD750: https://www.uglyhedgehog.com/t-694192-23.html#12196221

Fotoartist Loc: Detroit, Michigan

We all know how JPEGs are made. The question is, What resolution JPEG did you make? A 12 or a 6? You don't expect us to buy that this is a high res JPEG do you?

selmslie Loc: Fernandina Beach, FL, USA

You avoid it because the compression grid is not used when saving the TIFF even if you started from a JPEG.

Ysarex Loc: St. Louis

I believe I said just the opposite -- suggest you read.

Ysarex Loc: St. Louis

Yep, I believe I just said that: "You'll be able to avoid recompression damage."

Fotoartist Loc: Detroit, Michigan

The only bad things that will happen are when you put your thumb on the scale and increase the compression to prove your point.

Ysarex Loc: St. Louis

I would recommend not doing that. If you're suggesting that I did that you are wrong. What I saved for display here was created using the highest quality JPEG setting possible in PS.

Fotoartist Loc: Detroit, Michigan

JPEG noise. Where did you get that from? Do you mean artifacts? You won't get many artifacts if at all if you save at the lowest compression (12). And if you resave 1000 times you won't increase them either.

Fotoartist Loc: Detroit, Michigan

I don't buy it. No high resolution JPEG from a 12MP camera looks that bad. And what kind of test would show a "processed' and "edited" image without divulging the process?

DonVA Loc: British Columbia and New Mexico

Making a great image is a process that begins in your mind's eye and isn't over until its over. At each step you do the best you can with what you've got and each successive step builds on the one before.
An attitude of "fix it in post" means I'm not doing my best at this end and that means I wont get my best at the other end.

Fotoartist Loc: Detroit, Michigan

BS. There is such a thing as GIGO. And there is no excuse for that, But as an example, one need not set the white balance in camera before taking the picture as it can be done in post just as well if not better.

Ysarex Loc: St. Louis

The SOOC JPEG is from an older compact camera -- Samsung EX2F. I did nothing to it except to edit it in PS to get a result closer to my raw processing. I selected an image from that older 12 megapixel compact because I knew I'd have a better chance of showing JD750 what he asked to see. I multiple times noted that using modern higher res cameras typically swamps this type of degradation under the increased resolution. I'm not trying to put thumbs on the scale or present false information. If I were I wouldn't have qualified what I posted with the multiple remarks about higher res modern cameras nor would I have been forthcoming about using that older 12 megapixel SOOC JPEG and why.

IGBTQ2 Loc: California

Yea, Ima call BS too. It's not an attitude of fix it in post; the attitude is that I'll finish it in post... and sometimes what's in my minds eye can't be accomplished just in camera. 😉