Archive | Image Processing

Contrast enhancement – part 2/2

All right, now that we added some missing bricks, like Y’CbCr to RGB , we can finish our contrast enhancement started in the post Contrast enhancement – part 1/2. The goal is to tweak poor contrast images, like this one: And to make these pictures automatically and reasonably contrasted:   So let’s summarize, the idea is […]

Contrast enhancement – part 1/2

In the previous image processing posts, we built a luma histogram from a RGB picture. In the next posts, we will work on contrast enhancement. We will use the luma channel, and define 2 luma stretch points, one on the dark side, one on the bright side. So all the pixels having a luma value […]

Luma histogram

In the previous post we created 3 channels from the RGB original picture : Y’, Cb, and Cr. We will now look that the luma histogram, so using the Y’ channel computed in previous post. What is an histogram ? It is a graphical representation of the pixel value distribution in a picture. It could […]

Y’CbCr (“YUV”) conversion – part 1

Ok this week let’s try something a little bit more useful than random manipulation of one picture. Starting from the same beautiful Yosemite picture, we will convert it from RGB color space to Y’CbCr color space. Many websites can help you to get more background on Y’CbCr color spaces, and commonly called “YUV”. I am […]