imageData

[Rob Cozens]

>I'm a little confused about imageData.  How would I create an image, using
>imageData, with whatever colors I wanted for each pixel?
>
>Ex:  If the new image was 5 pixels by 5 pixels, with each pixel being some
>color that the user chooses, how do I handle imageData to build the final
>image?

Derek,

Per the Dictionary, "Each pixel is represented by four bytes of image 
data, with pixels numbered from the top left corner of the image, 
left to right, top to bottom.  The first byte consists of zeroes, and 
the last three bytes encode the amount of red, green, and blue 
respectively.  ...you can obtain the numeric value of any of the 
color channels for a given pixel using the charToNum function.  For 
example, the numeric value of the red channel for the tenth pixel is 
given by the expression, charToNum(char((4*9)+2) of the imageData of 
image."

Based on the above (untested):

on changeImageColor imageName,pixelColors
   get the imageData of image imageName
   put length(it) div 4 into pixelCount
   if the number of lines of pixelColors <> pixelCount then \
     return "Color list lines & pixel count mismatch."
   repeat with x = 1 to pixelCount
     put (x-1)*4 into pixelStart
     put line x of pixelColors into newColors
     put numToChar(item 1 of newColors) into char(pixelStart+2) of it
     put numToChar(item 2 of newColors) into char(pixelStart+3) of it
     put numToChar(item 3 of newColors) into char(pixelStart+4) of it
   end repeat
   set the imageData of image imageName to it
   return empty -- no error
end changImageColor

Note this assumes you pass a list of the new colors in RGB format, 
one line per pixel.  You might incorporate a different logic scheme, 
perhaps setting the new color based on the value of the original 
color.

Hope this helps.
-- 

Rob Cozens
CCW, Serendipity Software Company

"And I, which was two fooles, do so grow three;
Who are a little wise, the best fooles bee."

from "The Triple Foole" by John Donne (1572-1631)