Camera JPEG Over-Sharpened

[Frostbyte]

When an in-camera conversion to a JPEG image occurs, the algorithm for sharpening can over-sharpen certain types of images. Case in point is this shot taken of Niagara Falls.



In the close-up version you can see that each drop of water spray has a black halo around it.



If you don’t expand the image, it is not noticed. However, in post processing, any sharpening activity, such as Local Contrast Enhancement accentuates the condition and can make it very noticeable as in the following example.



To compensate at shoot time, I can, in some cameras, adjust the sharpening that is applied to Plus, Normal, or Minus, but not eliminate the sharpening altogether unless I can shoot in RAW mode. The documentation does not clarify what these three values actually accomplish, but rather provides a glimmer of hope that the situation can be minimized.

For Nikon cameras, there is also an Active-D Lighting setting which reduces the exposure value from 1/3EV to 1EV (depending upon the Flash usage) and performs a form of in-camera Local Contrast Enhancement which can be turned on or off.

I would like to simulate a sharpening reversal, but not a blur. What I am hoping to find is a global adjustment technique in Photoshop that can minimize or eliminate the effect of the black halos around each drop of water.

In Photoshop, is it possible to change, let’s say, any pixel in a selection with a value below a set limit, such as R:10,G:10, B:10 to an eyedropper selected value?

The goal would be to sacrifice the darkest blacks in the selection to obtain the conversion of the black halo to an adjacent color of either the water droplets or the background.

Alternatively, is it possible to select all the pixels within a range of an eyedropper selected value and change it to a different eyedropper selected value?

[jiro]

If based on your line of thought you can use the "color range" function to select that specific "color" and you can dial in the "feathering" by adjusting the range or fuzziness of that color range based on its tonal range. What you'll get then is a selection based on the color you chose and the fuzziness level.

I am assuming that you're going to such length because you have no more chance for a reshoot and do it in RAW Capture. I have never come across any website so far that discusses the actual algorithm of Nikon with regards to their in-camera sharpening process. If you want a simple reversal, you can use the Clarity slider in LR and slide it to the left to counter the added contrast that you want to lessen.

Your shot is already that sharp, Frank. Anything more than what I'm seeing and you're bordering to the limit of what looks natural for the human eye to notice. Just a thought for discussion.

[robmarshall]

Sorry, Frank. But the simple answer to this is shoot in RAW. The only people who shoot JPEGs with a good reason are editorial photographers and wedding photographers, simply because the don't have the time to process RAW files. This is a landscape shot, and as such there are always huge benefits in shooting RAW.

[Frostbyte]

Oct 16, 2011 18:48:32 GMT jiro said:

If based on your line of thought you can use the "color range" function to select that specific "color" and you can dial in the "feathering" by adjusting the range or fuzziness of that color range based on its tonal range. What you'll get then is a selection based on the color you chose and the fuzziness level.

I am assuming that you're going to such length because you have no more chance for a reshoot and do it in RAW Capture. I have never come across any website so far that discusses the actual algorithm of Nikon with regards to their in-camera sharpening process. If you want a simple reversal, you can use the Clarity slider in LR and slide it to the left to counter the added contrast that you want to lessen.

Your shot is already that sharp, Frank. Anything more than what I'm seeing and you're bordering to the limit of what looks natural for the human eye to notice. Just a thought for discussion.

Hi Jiro, yes, you are correct, going back for a reshoot would be a rare possibility and I'd like to be able to correct the issue in the existing image, if at all possible because of that. If I can't, then I may need to trash the image but I was hoping to save it.

I'll try the techniques you suggest and if I can even just move the result in the desired direction it may provide enough benefit to be worthwhile.

You say that the image is already sharp but my feeling is that the halos are already TOO noticeable to be acceptable. <sigh>

[Frostbyte]

Oct 16, 2011 19:15:58 GMT @robmarshall said:

Sorry, Frank. But the simple answer to this is shoot in RAW. The only people who shoot JPEGs with a good reason are editorial photographers and wedding photographers, simply because the don't have the time to process RAW files. This is a landscape shot, and as such there are always huge benefits in shooting RAW.

Hi Rob,

Actually, it's the ONLY answer when I am using my Nikon, but that's not the only camera I shoot with and none of the others can shoot in RAW mode. Which is why I am trying to minimize the issue for these kinds of images at the point of shooting. If I can't correct the issue then I'll have to toss the images that fit that situation. Fortunately, I've only come across less than a dozen shots where this is an issue out of several thousand shots that 'might' be worth keeping. Thanks for considering.

[Frostbyte]

Well Mr. Jiro, you’ve done it again! I tried reducing the black halos in the SOOC image by sliding the Clarity to the left in ACR and it reduced the halos sufficiently to make the image acceptable for further post processing.

I then, using your suggestions, went to the completed image as I wasn’t sure I could remember everything I did to get it to that state and I figured that this image had the worse black halos, so if I could fix them here I could fix them most anywhere. I zoomed in to clearly see the progress and here is what I started with.



1. Created a copy of the image layer (of course!).

2. Using the eye dropper, selected the white from a typical water drop as the foreground color.

3. Created a new layer and used Edit/Fill for the white foreground color.

4. Set Foreground color to Black, the color in the halos I want to replace.

5. Selected the image then Select/All and Select/Color Range.

6. Color Range will select (turn Red) the darkest black based on the current Foreground Color, and the Fuzziness slider (Set this to ~50) will control how many pixels close to the Foreground Color are selected.



7. Use Select/Invert then Layer/Layer Mask/Reveal Selection to apply a mask that sees through to the new layer below.



This gives you a layer where all the darkest black is now showing the white foreground color. We didn’t want to eliminate all the black as we didn’t want to start the sharpening process all over again.

8. We can now combine the masked image and the new layers using CTL+ALT+SHIFT+E.

9. All that is left to do is to blend the modified layer with the original, but only where the black halos are a problem and maybe not totally even there as we don’t want to lose the blacks and contrast elsewhere in the image.

Here is the finished result and it sure beats trying to change the halos manually!

[jiro]

I'm glad you sorted it out, Frank. Good on you.

[Frostbyte]

Oct 17, 2011 1:56:22 GMT jiro said:

I'm glad you sorted it out, Frank. Good on you.

You are so modest. All I did was to be just wise enough follow your excellent guidance.

[jiro]

You did all the work. I merely guided you.