Question

Ok. To be short suppose:

1. I have a monochrome image; And initially it represented in RGB color space.

2. I don’t know in what sequence I shall do this, but I need to convert image to YUV space (a) and load it into PictureBox control (b) and make few color scribbles;

3. And finally I need to learn/know somehow what pixels were colored.

   And how do I draw lines/dots on loaded image in PictureBox?

Have any ideas?

Answer 1

Converting a monochrome image from RGB to YUV is very simple:

Y = R
U = 0
V = 0

Y is the luminance, calculated as 0.299 * R + 0.587 * G + 0.114 * B, but as R = G = B for a monochome image, it’s the same as (0.299+0.587+0.114) * R which is simply 1 * R.

U is calculated as 0.436 * ((B - Y) / 0.886), but as Y = B it is always zero.

V is calculated as 0.615 * ((R - Y) / 0.701), but as Y = R it is alwaus zero.

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To draw lines on a Bitmap object, you use the Graphics.FromImage method to create a Graphics object for it, then use the DrawLine method to draw lines.

To draw pixels, use the SetPixel method of the Bitmap object.