Re: [Haskell-cafe] Pixel by pixel image processing

3 Jun 2015

      Thank you everybody!
*JuicyPixels* was the first package I have thought about, but I've mistaken
about its functionality and didn't mentioned it here.

*Sylvain*, thank you a lot! You've made my day!

ср, 3 июня 2015 г. в 14:52, Sylvain Henry :
...
Hi,
Here is a solution using JuicyPixels:
import Codec.Picture
import Codec.Picture.Types
main :: IO ()
main = do
   Right img <- readImage "test.png"
   _ <- writeDynamicPng "test2.png" (dynamicPixelMap circleImage img)
   return ()
circleImage :: Pixel a => Image a -> Image a
circleImage img = generateImage (\x y -> f x y $ pixelAt img x y) edge edge
   where
      edge = min (imageWidth img) (imageHeight img)
      f x y a = if x'*x' + y'*y' < e'*e'
            then a
            else colorMap (const 0) a
         where
            e' = edge `div` 2
            x' = x - e'
            y' = y - e'
Sylvain
2015-06-03 9:19 GMT+02:00 Geraldus :
...
Hi cafe!
I want to do some trivial masking manipulation on PNG images: take a
picture, crop it to square shape and then make a circular mask, i.e. take
all pixels that lies outside circle with radius equal to half of image
width and placed at image center and replace that pixels with zero opacity
once (hope this description is clear enough).
I've found two packages for image processing so far: `friday` [1] and
`unm-hip` [2], but can't figure out which of them suits my needs, maybe
there are some other packages I miss?
[1] https://hackage.haskell.org/package/friday
[2] https://hackage.haskell.org/package/unm-hip
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