ImageData:mapPixel
Transform an image by applying a function to every pixel.
This function is a higher order function. It takes another function as a parameter, and calls it once for each pixel in the ImageData.
The passed function is called with six parameters for each pixel in turn. The parameters are numbers that represent the x and y coordinates of the pixel and its red, green, blue and alpha values. The function should return the new red, green, blue, and alpha values for that pixel.
function pixelFunction(x, y, r, g, b, a) -- template for defining your own pixel mapping function -- perform computations giving the new values for r, g, b and a -- ... return r, g, b, a end
Function
Synopsis
ImageData:mapPixel( pixelFunction )
Arguments
function pixelFunction
- Function to apply to every pixel.
Returns
Nothing.
Function
Available since LÖVE 0.9.0
This variant is not supported in earlier versions.
Synopsis
ImageData:mapPixel( pixelFunction, x, y, width, height )
Arguments
function pixelFunction
- Function to apply to every pixel.
number x
- The x-axis of the top-left corner of the area within the ImageData to apply the function to.
number y
- The y-axis of the top-left corner of the area within the ImageData to apply the function to.
number width
- The width of the area within the ImageData to apply the function to.
number height
- The height of the area within the ImageData to apply the function to.
Returns
Nothing.
Examples
Brighten an image:
function brighten( x, y, r, g, b, a ) r = math.min(r * 3, 255) g = math.min(g * 3, 255) b = math.min(b * 3, 255) return r,g,b,a end imageData:mapPixel( brighten )
Add colored stripes to an image:
function stripey( x, y, r, g, b, a ) r = math.min(r * math.sin(x*100)*2, 255) g = math.min(g * math.cos(x*150)*2, 255) b = math.min(b * math.sin(x*50)*2, 255) return r,g,b,a end imageData:mapPixel( stripey )
source: http://khason.net/blog/hlsl-pixel-shader-effects-tutorial/ (broken 11/16. See blogs.microsoft.co.il or archive.org mirrors.)
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