The dialogue does some amazing things by specifying the position of pure black, pure white and the mid tones of an image in the images histogram. This adjustment in the digital darkroom is roughly analogous to increasing or decreasing the amount of light allowed to strike the paper in the "wet" darkroom.
It is sometimes hard to believe that such a small adjustment can make such an huge improvement to ...
Elements Levels have to do with modifying the image Histogram.
The Histogram is the visual representation of how many pixels are at each brightness level from Black (also called Shadows) with a value of 0 to White (also called Highlights) with a value of 255.
The ideal image histogram will have pixels at every brightness level from 0 to 255 - kind of like this one ...
Input Levels indicates where the Shadow (black - 1),
Highlight (white - 2), and
Mid-Point (middle gray - 3) sliders are presently located.
The Eyedroppers - 4 - can select Shadows, Highlights and Mid-tones.
The Tonal Range - 5 - of this image is from 0 to 255 but most images seem to be less than the full 255 levels of brightness.
When an image does not cover the full 255 levels of brightness its histogram can be stretched with the Levels command so that all of the brightness levels are included in the image.
The stretching is achieved by moving one or all of the three sliders and the amount of moving will depend on each images histogram.
Let's take a look at an image ... I was wandering about with my trusty Olympus E-300 one day and came decided that the front of this church was worth some space on my compact flash.
The picture is OK but the application of some Elements Levels adjustments can perk it up somewhat.
Here is the histogram for this image and it is easy to see that the pixel values do not stretch all the way from 0 to 255. When I ran my cursor from left to right on the histogram the brightness levels only went from 14 to 214 - that is only 200 levels of brightness - yikes - no wonder it looks flat - there are a full 55 brightness levels missing!
The numbers are not important - I am simply using them to demonstrate what is happened with the Elements Levels adjustments ...
Bring up the Levels Dialogue - Image > Adjustments > Levels or Ctrl-L (Windows) or Cmd-L (Mac) or add a Levels Adjustment Layer. I'm partial to the last method because the Adjustment layer is easier to work with.
Now move the Shadow slider to the right until it meets the edge of the Histogram at 18 and move the Highlight slider to the left until it meets the Histogram at 225. These numbers will change for every image.
What this does is take (in my example) the 200 levels of brightness and stretched them across 255 levels.
The new numbers for the Shadow and Highlights are now visible in the Input Levels boxes.
Here is the resulting image after the adjustment ...
And the new Histogram ...
You may notice that the Histogram now looks different in a couple of ways.
Firstly - the histogram stretches from 0 to 255 - nice.
Secondly - the histogram has holes in it - weird. Well it's really not weird when you think about it.
The adjustment that was made has stretched 207 levels of brightness over 255 levels of brightness so something has got to go.
There are areas with no brightness present but it is difficult, if not impossible to see where they are missing and darn - the image looks so much better!
This always happens with the elements levels adjustment.
The really good thing is the improvement in the image. It is brighter with more contrast which is more like I remember it from that emotional point of view.
There is a problem with the image, however. In the original, kind of flat image, some detail could be seen through the doors of the church and after the Elements Levels adjustment these details are gone ...
This is easy to fix - happily. The Elements Levels dialogue includes a Layer Mask and that is how to bring back the missing details.
The Elements Levels Adjustment layer contains a Layer Mask - that is the little white thing (outlined in red) to the right of the Levels part of the layer.
Layer masks are very powerful and very useful. The Layer Mask, for all intents and purposes ...
is where the Levels adjustment resides. If we paint with black with the layer mask selected then that portion of the adjustment will be removed and the original image (contained in Background Copy) will show through.
Painting with black punches a hole through the mask so the un-adjusted information underneath the mask is visible.
The procedure to painting on the layer mask to reveal what is underneath is easy and straightforward ...
That is all there is to it.
Here is the end layers palette and a screen shot of the actual mask (Alt-Click on the mask to get the view of the mask) ...
Wasn't that easy, really?
Now for a more difficult image ...
Like this one ... Max the Staffie and Tabitha the Mini playing with Max's favorite toy ...
And here is the histogram for the image ...
Can an Elements Levels adjustment help this image? Of course it can!
Obviously, no movement of the black point slider is needed but the white point slider can go a long way. When you look at the histogram closely you can see that there is a very small thin line on the white side running along the bottom of the histogram.This means there is some brightness here so that is where I placed the white point slider. The image improved a lot but was still way too dark so I moved the mid-point slider to the left (from a value of 1.0 to 1.58). In a situation like this the Mid-Point slider can be very useful, indeed.
After moving the White Point slider to its new home the image was way too contrasty - I figured I was a Levels Tutorial failure! Luckily, I remembered to move the Mid-Point slider to add some shadows back into the image.
This is not exact science - there are some general guidelines and suggestions but after that - whatever works!
To the right of the White Point slider there are some areas of brightness but I ignored them.
This image contains 201,600 pixels (I ran my pen from right to left in the histogram box and it told me how many pixels are there). The thin line across the bottom, at its thinnest, contained 20 to 75 pixels so I moved the slider to a point with more pixels. It did not cause a problem because there are no brightness levels in the highlight area that are tall spikes, also known as clipping.
The purists may debate that but ....
This is the image after the change ...
And the new histogram with the missing parts showing as blank areas.
This histogram is not perfectly balanced but the image is much better, isn't it? It is easy to see the texture and colors on Max's side now.
Away you go - do lots of scrapbook Levels adjustments - make mistakes and enjoy your successes. Your final images will be the better for it!
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