Wrong pixel values.

[Atirag]

Hello I have an image that is mostly yellow and I tried to turn it into a grayscale image by using this.

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MagickQuantizeImage(image_wand,256,GRAYColorspace,0,MagickFalse,MagickFalse);

and it worked the image turned into grayscale and I saved it as a new file.

I later used that same file but now I need to use the grayscale value of the pixels. The grayscale value is supposed to be any of the RGB colors since they're supposed to be the same. Yet when I use this

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PixelGetRed(pixels_wand[i])

I get many 0 values so I printed each pixel RGB and I got different values mainly 1 with PixelGetRed or PixelGetBlue but never the same.

Then I used the image without a grayscale conversion and I got the same. The weird thing is that the image is mostly yellow so I would expect PixelGetRed and PixelGetGreen to return 1 both but I mostly get 1 on Red and 0 elsewhere or 1 on Blue and 0 elsewhere.

Any ideas what might be happening?

[anthony]

Quantize does not grayscale the image. It reduces colors.

The colorspace for it is for the determination of how close colors are, not for setting the colorspace of an image.

[Atirag]

Thx Anthony!

And how can I change the image to grayscale?