Weird B&W jpeg exports from CS6?

I noticed recently that I had issues with saving edited B&W pictures (RAW opened in ACR and converted to 16-bit greyscale, then adjusted in PS as needed, and finally turned to 8-bit and saved as jpeg).

Weirdly, it's like the entire picturegets normalized a bit, with deep shadows being brightened a bit. Since it's done to a file that's 8-bit at that point, there's quite a bit of posterization.

If, however, I save for web (instead of regular save), this doesn't happen and the resulting file looks like my 16-bit edit.

Any ideas as to why that's happening?

Since it sounds like the difference is between Save As and Save for Web, I would suspect a color management problem. I suggest you check to see if both images are being saved with the same color profile (sRGB, for example).

Is this only when the image has been turned to greyscale before PS, or after as well?

I ask because I would naturally do ALL my processing in PS and save the result when I've finished.

In case anyone has the same question in the future: it turns out that while I set up my ACR exports to sRGB by default, it uses a different color space when converting it to B&W in ACR. I hadn't noticed that it switched to Grey 2.2. Having corrected it, issue is now gone. Fifty points for Eyeball2!

Armis,

I'm still confused by this problem you report because I am unable to replicate it. I've tried to repeat your steps, but no form of B&W conversion I do generates an image that is "normalized" with "posterization." Could you please explain more fully what steps you take that result in the bad image you report?

It sounds like this:

1. Set ACR to 16 bit sRGB mode.
2. Open Raw, convert to Grayscale inside ACR using the (default) Gray Gamma 2.2 colorspace and retaining 16bit mode.
3. Make edits inside ACR?
4. Pass to Photoshop as 16bit Gray Gamma 2.2.
5. Edit (how much) inside Phtoshop.
6. Convert to 8 bit mode.
7. Save as jpeg using Save As (not Save for Web) using what quality?
8. View that jpeg and see normalization and posterization.
9. Repeat steps 1 thru 6, save using Save for Web (what settings?), view that jpeg as OK.

In your last post, you pointed at the Gray Gamma 2.2 colorspace as the problem and say you "corrected it". What correction did you make?

Redcrown wrote in post #17184028
Armis,

I'm still confused by this problem you report because I am unable to replicate it. I've tried to repeat your steps, but no form of B&W conversion I do generates an image that is "normalized" with "posterization." Could you please explain more fully what steps you take that result in the bad image you report?

It sounds like this:

1. Set ACR to 16 bit sRGB mode.
2. Open Raw, convert to Grayscale inside ACR using the (default) Gray Gamma 2.2 colorspace and retaining 16bit mode.
3. Make edits inside ACR?
4. Pass to Photoshop as 16bit Gray Gamma 2.2.
5. Edit (how much) inside Phtoshop.
6. Convert to 8 bit mode.
7. Save as jpeg using Save As (not Save for Web) using what quality?
8. View that jpeg and see normalization and posterization.
9. Repeat steps 1 thru 6, save using Save for Web (what settings?), view that jpeg as OK.

In your last post, you pointed at the Gray Gamma 2.2 colorspace as the problem and say you "corrected it". What correction did you make?

That's pretty much exactly it (for reference, I'm using what I think is the latest ACR version for CS6). I did make some edits in ACR and minor edits in Photoshop (mostly clone stamping out a couple of ugly cranes in the background), then used my two usual actions:
- one that does local contrast sharpening (two passes of USM with different parameters, basically)
- one that flattens, converts to 8 bit mode, and saves as jpeg quality 12.

That jpeg showed slight tone shifts (slightly lightened shadows and slightly darkened highlights) and posterization, which I noticed most in the shadows - in fact, the reason I noticed is that two adjacent, tonally similar but distinct, areas of the image suddenly looked like one unified blotch since the tones had shifted towards each other.

Going back to the original edit (before application of the second action, but after the first) and saving for web (quality 100, no resizing) yielded a jpeg that did not have these issues, and matched what I had on-screen in Photoshop.

In the step-by-step you outlined, I then converted to Grayscale in ACR using sRGB instead of Gray Gamma 2.2, and the issue appears to be gone.

The tonal shifts were very subtle, to be honest, since that wasn't the first time I did B&W in ACR and I hadn't noticed before, but that one picture I was working on sure brought them out.

Armis,

One more question...

When you compared two versions of your image and noticed differences, what programs were you using to make the comparison?

In other words, were you comparing the image as it appeared in ACR to the way it looked in Photoshop CS6? Were you comparing how it looked in Photoshop to how it looked in some non-Adobe program, like a browser (IE, Firefox, Chrome) or a viewer such as FastStone, Windows Photo Viewer, Picasa, etc.?

BTW, I looked at your website. Very nNice work. I envy your travel.

I originally spotted the difference when viewing the flattened, 8-bit (but unsaved) image in Photoshop vs. the saved jpeg in Windows Photo Viewer or whatever the default image viewer is called. Then I saved for web under another name and flipped between the two saved jpegs quickly in the Windows viewer (left/right keyboard arrow) and still saw the difference.

(Thanks! )

Windows picture viewer is not colour managed, just like most web browsers. Using anything other than sRGB is going to present issues. The colour space that you need to use is really dependant on the final use. If that use is the web, or viewing on the OS's in built application then you should always use sRGB as your final colour space. Save for Web will by default always convert an image to sRGB, as that is the web default too.

If you view the images saved in Greygamma2.2 in a colour managed viewer, PS would be fine, then it will look fine.

With colour images this is often seen as colours looking muddy. Obviously with mono images you only see it as a shift in tone.

Alan

Thanks for the answer, Armis.

BigAl already explained why you saw differences in your images. Color managed vs. non color managed viewers.

A true grayscale image (one byte per pixel insted of 3 bytes in an RGB image) plus the Gray Gamma 2.2 colorspace is kind of a wierd duck. Not suprising that some viewers give a bad display.

Some software will generate differences in display even if they are color managed. While color management is a "standard", not everyone follows the standard 100%. Here is a website that shows an interesting difference between Microsoft IE and Photoshop on the same sRGB image.

http://www.epaperpress​.com/monitorcal/profil​e.html

The monitor profile is another source of potential difference. The popular FastStone viewer has long ingored the system monitor profile. Thus FastStone always displays images differently than Photoshop.

What really surprises me is that you are actually seeing any change between sRGB and Grey 2.2. I produced some monochrome files for printing on Ilford black & White photo paper recently. I just went back and checked and I can see no change in the display between using Windows Picture Viewer (under 32bit Vista) and PSCS5 to view the images. I had a look at detail at both ends of the tonal scale.

Alan

Well, it was fairly obvious on those two:
- first is the image properly converted to sRGB
- second is the image converted to sGray, which is what Gray Gamma 2.2 looked like on the - I assume - non-color managed default image viewer (I'm happy to upload the original, but I suspect your browser will handle the profile just fine).

If nothing else, look at the transition between the cyclist on the right-hand foreground and the background...