How to Use Calculated Color Values with ColorMatrix?
- by Otaku
I am changing color values of each pixel in an image based on a calculation. The problem is that this takes over 5 seconds on my machine with a 1000x1333 image and I'm looking for a way to optimize it to be much faster.
I think ColorMatrix may be an option, but I'm having a difficult time figure out how I would get a set of pixel RGB values, use that to calculate and then set the new pixel value. I can see how this can be done if I was just modifying (multiplying, subtracting, etc.) the original value with ColorMatrix, but now how I can use the pixels returned value to use it to calculate and new value.
For example:
Sub DarkenPicture()
Dim clrTestFolderPath = "C:\Users\Me\Desktop\ColorTest\"
Dim originalPicture = "original.jpg"
Dim Luminance As Single
Dim bitmapOriginal As Bitmap = Image.FromFile(clrTestFolderPath + originalPicture)
Dim Clr As Color
Dim newR As Byte
Dim newG As Byte
Dim newB As Byte
For x = 0 To bitmapOriginal.Width - 1
For y = 0 To bitmapOriginal.Height - 1
Clr = bitmapOriginal.GetPixel(x, y)
Luminance = ((0.21 * (Clr.R) + (0.72 * (Clr.G)) + (0.07 * (Clr.B))/ 255
newR = Clr.R * Luminance
newG = Clr.G * Luminance
newB = Clr.B * Luminance
bitmapOriginal.SetPixel(x, y, Color.FromArgb(newR, newG, newB))
Next
Next
bitmapOriginal.Save(clrTestFolderPath + "colorized.jpg", ImageFormat.Jpeg)
End Sub
The Luminance value is the calculated one. I know I can set ColorMatrix's M00, M11, M22 to 0, 0, 0 respectively and then put a new value in M40, M41, M42, but that new value is calculated based of a value multiplication and addition of that pixel's components (((0.21 * (Clr.R) + (0.72 * (Clr.G)) + (0.07 * (Clr.B)) and the result of that - Luminance - is multiplied by the color component).
Is this even possible with ColorMatrix?
