Recently we looked at how histograms show the tonal data of an image, now lets put them to some practical use.
Histograms are ideal to help us understand the contrast in our images. When a picture seems a bit “foggy”, we can look at the histogram and see exactly where the graph is unbalanced. Maybe the tonal information is mainly in the middle of the histogram, thereby showing a lack of both shadows and highlights; or perhaps the graph is mainly to the left of the centre showing that, while the dark tones are fine, the whites are underexposed.
Histograms are a much misunderstood species, but can be an incredibly useful tool for any photographer and Photoshop artist. In my previous tutorial about clearing a colour cast I have already shown one example of how you can use these graphs; there are countless other ways they make themselves invaluable. And it’s not just in Photoshop that histograms are a useful guide. They can also be found in the display options of all digital SLR cameras, and most point-and-shoot cameras, and can be a useful aid in achieving correctly exposed photos.
I use them constantly while I’m working in Photoshop, so before I write any more tutorials that use these I’d like to give a quick explanation as to what it is you’re looking at, and why they’re so helpful.