Legacy ImageMagick Discussions Archive

hi,
unluckely I'm a complete newbe using the magickwand within c-lang. first of all my magickwand-version is the debian-sid (8:6.8.9.9-7.2)

I tried to generate a small test image with 3 colors in it.

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$ convert -size 4x4 xc:red xc:green xc:blue +append a.png
$ identify -format "%k %wx%h %f\n" a.png
3 12x4 a.png

the goal to reach was printing out the palette index for each pixel. so I wrote a small program

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// cc -o `pkg-config --cflags --libs MagickWand` -o c c.c

#include <wand/magick_wand.h>

int main(int argc,char **argv)
{
	MagickWand *m_wand = NULL;
	PixelWand *color = NULL;
	MagickPixelPacket pixel;
	PixelIterator* pixel_iterator = NULL;
	
	int x, y;
	size_t width, height;
        size_t indexedcolors;
	double R, G, B;
	char* file = argv[1];
	
	MagickWandGenesis();
	
	m_wand = NewMagickWand();
	color = NewPixelWand();

	MagickReadImage(m_wand, file);
	
	width = MagickGetImageWidth(m_wand);
	height = MagickGetImageHeight(m_wand);

	indexedcolors = MagickGetImageColors(m_wand);

	printf("image: %s width: %d height: %d countindex: %d\n", file, (int) width, (int) height, indexedcolors);

	for (y = 0; y <= (int)height; y++)
	{
	   printf("line: %03d pixel: ", y);
	   for (x = 0; x < (int)width; x++)
	   {
	      MagickGetImagePixelColor(m_wand, (ssize_t)x,(ssize_t)y, color);
              printf("%02x ", PixelGetColorCount(color)); 
	   }
	printf("\n");
	}

	MagickWandTerminus();

	exit(0);
}

the outcoming result is:

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image: a.png width: 12 height: 4 countindex: 3
line: 000 pixel: 00 00 00 00 00 00 00 00 00 00 00 00 
line: 001 pixel: 00 00 00 00 00 00 00 00 00 00 00 00 
line: 002 pixel: 00 00 00 00 00 00 00 00 00 00 00 00 
line: 003 pixel: 00 00 00 00 00 00 00 00 00 00 00 00 
line: 004 pixel: 00 00 00 00 00 00 00 00 00 00 00 00

why does this not work?

thank you in advance for helping me
murmel

You want an index, but asked for PixelGetColorCount().

Perhaps PixelGetIndex() would provide what you want.

thank you for reply ... I didn't recognized that function so far.

it seems to work with a testimage.PNG produced by convert

but the same testimage formated as a GIF - it doesn't (using a palette with only 7 colors).

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IndexPacket PixelGetIndex(const PixelWand *wand)

as i mentioned the typedef IndexPacket is equal to "unsigned char". which type is used if image ownes more than 255 colors/8bit

many thanks to the comunity
murmel

Legacy ImageMagick Discussions Archive

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getting the colormapindex for each pixel

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Re: getting the colormapindex for each pixel