Pacific Northwest Nature Photographers Tips, Tricks, Techniques & Tutorials
Selective Contrast Enhancement Technique
by Phil Kuglin
by Phil Kuglin
Several of you asked me to explain the selective contrast enhancement techniques I learned in Barry’s course. Here is a mini tutorial using the “Mount Hood w/ beargrass” image I posted. The procedure was done to boost the contrast and brightness of the middle ground trees.
First here is the image before the procedure:
And after the procedure:
The Procedure
1. Select the top most layer in the layer palette and then create a new curve adjustment layer (layer/new adjustment layer/curves).
2. Increase the size of the curves palette by mouse clicking on the lower right corner icon in the palette (it may be maximized already). Next increase the lines the curve shows by alt(option) clicking inside the curve area. Finally mouse click each intersection of the vertical and horizonal lines to lock down each point on the curve.
The palette will look like this:
3. Next, find the tonal range on the curve of the area you want to adjust. You can do this by mouse clicking on the area of the image you want to adjust. When you do this a small empty circle is placed on the curve at the area's tonal range. You then hold down the mouse button and drag the eye dropper around the area of the image you want to adjust and watch the circle on the curve.
For this image I mouse clicked where the red "X" in the following image:
This gave the following infomation in the curve palette:
I dragged the eye dropper around this area of the image to use where else on the curve this tonal range was.
Here is another point:
This gave the following infomation in the curve palette:
This gives you an idea of where to adjust the curve.
4. Now I adjusted the curve in that area and created a "mini S curve" to just adjust the area of the trees. Since I wanted to boost all channels I used the RGB channel. One can also limit the change to just a single channel by selecting the channel in the top drop down combo box. This would also allow you to do color correction at the same time. I over did the adjustment since I can limit the amount of the change later through the mask layer. Also, do not worry about changing any other area of the image since you are going to limit the adjustment to selective areas by using the mask layer associated with the curve adjustment layer.
This is what the "mini S curve" looks like:
5. Next I want to adjust the level of the entire mini S curve. I selected multiple points of the curve by holding down the Shift key and mouse clicking each point in the cuve I want to move.
I selected the following 4 points (they are black dots instead of hollow ones):
Next I dragged all 4 selected points up and to the left to boost their level (brightness).
The curve now looks like:
6. I hit "OK" in the curves palette and accepted the changes. I next hit control-I or command-I to invert the mask to hide all (paints the mask black). I then hit the "d" key to select default colors for the foreground (white) and background (black) colors.
7. Next, I hit the "b" key to select the brush tool and selected a large soft brush with an opacity of 100%, flow of 5-7% and turned on the air brush option. To make the brush soft I choose a hardness of 0%. The air brush option allows you to continuely paint as long as you have the mouse button down with the flow selected until you reach your opacity setting (as long as this is done in one procedure i.e. until you release the mouse button, once you release the mouse button the opacity count is reset back to zero). In this case it doesn't matter since the opacity is set to 100%. Now I simply painted the white foreground color into the mask in the areas I wanted the adjustment to show.
Here is a screen capture of the brush tool setup:
Here is a screen shot of the final mask I ended up with:
I used this procedure in several places on this image to adjust different parts of the image. For example I used just the green channel in a curve adjustment layer to boost the grass in the foreground.
Go ahead and give it a shot.