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Re: Cannot Set Image Pixel to a Random Colour using GD

by Fletch (Bishop)
on Dec 24, 2022 at 13:57 UTC ( [id://11149058]=note: print w/replies, xml ) Need Help??


in reply to Cannot Set Image Pixel to a Random Colour using GD

Handwavy (early and my morning caffeine hasn't kicked in) but if you're trying to uniformly desaturate all colors what I'd do would be to walk the pallet instead (not swapping the image to true color of course):

  • Get the total number of pallet entries
  • For each index 0..$num_colors
    • Fetch the rgb for the index
    • colorDeallocate that index
    • Compute your new desaturated color and then colorAllocate it back (which should (?) put it back in the recently freed index)

The cake is a lie.
The cake is a lie.
The cake is a lie.

Replies are listed 'Best First'.
Re^2: Cannot Set Image Pixel to a Random Colour using GD
by ozboomer (Friar) on Dec 25, 2022 at 10:15 UTC

    An interesting, probably slicker approach... but I wonder if there may be something like a 'refresh' of the palette required?

    As it stands, I don't think I'm dealing with a 'palette-ed' image here:-

    c:\> ffprobe -hide_banner ruddy.png
Input #0, png_pipe, from 'ruddy.png':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: png, rgb24(pc), 320x234, 25 fps, 25 tbr, 25 tbn

c:\> mediainfo ruddy.png
General
Complete name                            : ruddy.png
Format                                   : PNG
Format/Info                              : Portable Network Graphic
File size                                : 84.9 KiB

Image
Format                                   : PNG
Format/Info                              : Portable Network Graphic
Width                                    : 320 pixels
Height                                   : 234 pixels
Bit depth                                : 24 bits
Compression mode                         : Lossless
Stream size                              : 84.9 KiB (100%)

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