Modern digital cameras are amazingly smart. Yet at times you get a picture that misses the mark. Here is an example of a photo that is underexposed – it looks dark and muddy.
When you click on Fix and then Adjust Exposure you see the various controls and a histogram. The histogram is that little graph. It shows the distribution of the pixels from the full black one on the left end to the full white ones on the right end. The more pixels of a particular brightness the higher the graph at that point. For this picture you see two peaks in the histogram. The lower peak on the left, dark, end is from the darker background behind the blossom. The high peak is produced by the white flower petals. Except here they are not white but rather gray. Note that there are no pixels shown for a little stretch on the black – left end, and none for a rather longer interval on the white, right, end. The picture contains no real black or very dark areas and no full white pixels. That is why the picture is rather dull looking.
Now there are a number of ways to make this into a better photo. Auto adjust almost always does a fine job. With this picture it would improve it greatly. You can also use the controls for Brightness, Contrast, Shadows, Highlights and others. Here I want to tell you about the controls right below the histogram display. See the two slider controls, one at the left bottom corner and the other at the right bottom corner of the histogram. Note the left slider has a black square in it and the right one a white square. With the white point control you can set the full white point to any point along the graph. Same with the black point control.
Since the picture has no really white pixels, we can slide the white point slider to the left to just where there are pixels. These will become full white. If you move the slider farther to the left all the pixels to the right of it will become full white. Not normally a good idea. As you move the sliders you can see the changes right there in the picture.
As an exercise for this blog, I have also moved the black point slider up to the first dark pixels. This sets the darkest part of the background to full black. As always, they important thing is to experiment. The best result is the one that makes you happy.
When you are satisfied that the picture looks good to you, just go back to the thumbnails to see if there are others to improve. Windows Live Photo Gallery will save your settings so when you look at it the next time the picture histogram will be stretched out fully like here.
To fully appreciate these controls you need to experiment with them. Enjoy!