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Author Topic: Challenge #38, Sharpen using Target RGB  (Read 12231 times)
Fred A
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« on: December 28, 2014, 03:44:28 PM »

Your challenge is to show screen snaps of using Sharpen with target RGB

Situation:
The shot has a lot of foliage that (as we all know) sharpens too quickly and too aggressively most of the time.  That leads to limiting our sharpening to a low extreme because we don't want trees and grass to look over-sharpened.

By clicking the the EQ button in the editor screen, we see a bunch of choices on what to target.
We can select to target a certain tone. That works fine for 80% of the needs, but that selected tone can be found in other places in the image in near shades of the clicked on tone. That will sharpen too.
For example, click on a yellow flower, and wherever there is 'similar +/-' yellow in tree leaves and bushes, that will sharpen too.

But, if we use, Target RGB, and select a specific tone, we have narrowed the colors that will be included to a very small few.

Let's look at the "tone/color" of the building in screen snap #079. It's a sort of beige tan, I would say.
But in our digital color world it has a value averaging RGB at 230, 198, 164.  (Just run your  mouse over the area and read the values for yourself.)
That means that the red value is 230, the green is 198, and the blue was 164 on that pixel I was looking at. (This information is not really that important. Only to show the principle of the Target RGB)
The yellow tree leaves read out as 219, 181, 37....  close, but the tree does not sharpen. (The numbers are too far off from our selected target click!)

So we select Target RGB from the list. Then we use the dropper to click on our selected color.
The EQ slider pops all the way to the right for a good reason.
It is starting at the tightest leeway we want to sharpen around the selected colors.
So we add some "throttle to the engine. a 4/400 to the Radius and strength. (Just a place to start)
If we now, just for the getting the hang of it, slide our mouse pointer around the pixel area we selected, we get various readings of RGB, some higher and some lower, but close.
So let's move that slider a skinch to the left and see that it says 95% now. What that accomplishes is to widen the allowed passing of tone through the filter so other shades will be sharpened that are slightly more or less saturated. (Move that slider to 90 or 85% and a lot more areas that contain similar color will sharpen.
We can effectively sharpen the building color and nothing else.

That is the important aspect of Target RGB when sharpening an image.

Now look at the 4 samples.
079 shows the house sharpened. 080 shows sharpening off.
It is easy to see the house sharpened and not sharpened, but I want to focus your attention on that yellow green tree behind the house.
079, 080.... the sharpness of the tree is the same. The building sharpening is obvious.  (Getting the idea now?)
Let's look at snaps 081 and 082.  Look at the stone all sharpened and the tree branch on the right side unsharpened even though the shade is not too much different from the building.
If I were to move the EQ slider to 90 or 85%, you would see the branches and the yellow tree sharpen up too. (we loosened the filter and allowed more more similar tones to get sharpened)

The settings I used for this challenge were a 4/650 in the Radius and strength.

In the next post, you can see the actual image. Picture taken by Terry Mann, our own Terry.
The integrity of the image is maintained, while only the building got some sharpening.
A very useful tool!!
OK Kids. (I used Terry's picture because I need a shot with a lot of greenery vs. something I wanted to sharpen.) Now find an image that will work for you and report back with results.
Thank you!
Have fun!
Fred
« Last Edit: December 29, 2014, 10:12:39 AM by Fred A » Logged
Fred A
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« Reply #1 on: December 28, 2014, 04:59:13 PM »

Here's Terry's shot... with a touch of Sharpen RGB

Now let's see what you have!
Fred
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Jeff
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« Reply #2 on: December 28, 2014, 05:30:28 PM »

That is a good instructional Challenge.

I have some difficulty with Target RGB

I will have a go at it sometime using your specific instructions.

Trouble is I am still working on Terry's cut out Challenge, I have managed a nice © cut out.

Jeff


 
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Fred A
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« Reply #3 on: December 28, 2014, 07:48:30 PM »

As Barbara instructed me, find some way to keep Jeff out of the pub, please!
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