Starting at square one with image processing

James Hurley jhurley0305 at sbcglobal.net
Fri Jul 6 18:51:56 CDT 2007


I've discovered that I have no idea what's going on with the  
imagedata function.

I thought that the imagedata was a pixel by pixel map of the image. I  
tried the following handler to look at each pixel of my image:

on mouseUp
   put the name of image id 1014 into tName
   put the imagedata of tName into tData
   set the savedImageData of tName to tData
   --put the imagedata of img "basic.png" into tData
   put 0 into tCounter
   repeat for each char tChar in tData
     put charToNum(tChar) into tNum
     if tCounter mod 4  is 0 then put cr after results
     put tNum&comma after results
     add 1 to tCounter
   end repeat
   put results into field 1
end mouseUp

And I got the following in field 1:

0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
0,156,0,2,
etc.

This was the imagedata of a short red line segment painted with the  
red pencil.

I thought each line above represented successive pixels across the  
image--left to right and top to bottom.

Not so.

This is really screwy. If I set the imagedata of my image to the   
imagedata of itself, it is transformed from a short red  line to a  
solid red square. Actually that is what I would have thought the  
column above represented.

You image people out there live in a different world. I'm sure I'll  
get this in time, but right now I see that I was living in a fools  
paradise when working with graphics objects.

Jim Hurley




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