First of all Ill explain what I try to do, just in the case that someone comes up with a better approach I need to blend too images using the "color" stile from photoshop (you know, the blending methods: Screen, hard light, color ... )
So, I have my base image (a png) and WriteableBitmap generated on execution time (lets call it color mask). Then I need to blend this two images using the "color" method and show the result in a UI component.
So far what Im trying is just to draw things on the WriteableBitmap but I'm facing unexpected behavior with the alpha channel.
My code so far:
// variables declaration
WriteableBitmap img = new WriteableBitmap(width, height, 96,96,PixelFormats.Bgra32,null);
pixels = new uint[width * height];
//function for setting the color of one pixel
private void SetPixel(int x, int y, Color c)
{
int pixel = width * y + x;
int red = c.R;
int green = c.G;
int blue = c.B;
int alpha = c.A;
pixels[pixel] = (uint)((blue << 24) + (green << 16) + (red << 8) + alpha);
}
//function for paint all the pixels of the image
private void Render()
{
Color c = new Color();
c.R = 255; c.G = 255; c.B = 255; c.A = 50;
for (int y = 0; y < height; y++)
for (int x = 0; x < width; x++)
SetPixel(x, y, c);
img.WritePixels(new Int32Rect(0, 0, width, height), pixels, width * 4, 0);
image1.Source = img; // image1 is a WPF Image in my XAML
}
Whenever I run the code with the color c.A = 255 I get the expected results. The whole Image is set to the desired color. But if I set c.A to a different value I get weird things. If I set the color to BRGA = 0,0,255,50 I get a dark blue almost black. If I set it to BRGA = 255,255,255,50 I get a yellow ...
Any clue !?!?!
Thanks in advance !
