Level's eyedroppers

In this tutorial, in a short while, we will learn hot to to set the black and the white point, by using the eyedroppers contained in the Levels panel. This could be very appropriate for some scanned pictures.

First of all we add a new Level's Adjustment Layer, by clicking the half black and half withe icon at the bottom of the Layers panel. A new Adjustment layer will be added above the selected layer (in this case just above the background).

Now we have to sample in the image to set the black point. It should be hard to do, because we don't have the Superman sight to check the darkest pixel. Someone use the trick to move the black slide, of the input levels, to the right by pressing Alt key on the keyboard. But I prefer the following clue.
For the black: pretending that everything should be bright, which area would be the last to become white? Just move the white slide to the left and you'll see the answer. Don't choose any eyedropper and Shift+click on the spot to put a mark (#1), then bring the slide back to 255.

Now we can repeat the same, but opposite, for the white point.
Pretending that everything should be dark, which area would be the last to become black? This time move the black slide to the right in input levels and see the answer.
Don't choose any eyedropper and Shift+click on the spot to put a mark (#2), then bring the slide back to 0.

Pick the white eyedropper (last on the right) and click on the mark #2 in the picture.
In this manner we set the white point. In the Info panel we can see the values before, and values after the click.
Repeat the same for the black point clicking on the mark #1. We have set white to 255/255/255 and black to 0/0/0.

If the final effect is to "strong", I suggest to decrease master opacity of the adjustment layer.
In the picture we can se the values changing again. This last tip is specially indicated for whom want to print the picture. Who else need to publish it on internet could skip this last step.

SOURCE

technorati tags:photography, level's-eyedroppers, photoshop