In art, a value (or tone) is how light or dark a colour is. If you're learning to paint or draw, a good place to start is by doing value studies. These are small loose sketches in greyscale that show where shadows fall and highlights appear. These are particularly useful when the subject is more complicated, when it's hard to see through the colours to show the subtle shadows.
If you're learning to paint or draw, value studies are a sure-fire way to improve both your artwork and how you visualise references in your mind. People often use photo editors to convert a colour photo to black and white... this is helpful but this app goes further.
By using Value Study, you're able to flick between levels of detail. Maybe you want to start with just black and white to get a base down, then add in extra values one by one to build up your understanding of the reference you are studying.
You can even take it a step further and select all areas that have a matching tone. Click one of the values along the bottom in the greyscale palette to see all areas that match it in the image, so you can focus in on one value while painting it. For example in a portrait, this could mean seeing how different parts of the body have the same amount of shadow despite potentially looking wildly different when viewed in colour.
Value Study is a tool, not to replace your own value studies but to enhance them and especially to help beginner artists have some idea how where to start when looking at complicated reference imagery.
