MagickWand equivalent of -channel RGBA

[J2T]

Hi guys,

i'm looking for the equivalent of the -channel RGBA command line option.

The reason is that i like to blur a image with transparency information. I get the same result as described here with the yellow circle with the black creeping pixels at the outline.

So how i can apply the -channel RGBA with MagickWand to fix that?

Thanks!

[el_supremo]

I think that the MagickWand equivalent is:

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MagickSetOption(magick_wand,"channel","RGBA")

Pete

[J2T]

Thanks Pete for your reply.

I call this right before MagickBlurImage() but it doesn't work as my test image still has the creeping black pixels.

[J2T]

I tried to find a workaround but always get stuck. Maybe some of you can help me out with this?!

(I use c# + P/Invoke and my test image is a yellow square on a transparent background)

1.

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 IntPtr newWand = MagickMergeImageLayers(image, ImageLayerMethod.FlattenLayer);
MagickBlurImage(newWand, 0.0, 8.0);

with the result, that the blur is correct (because of the white color of the transparent pixels i guess) but the background is white (alpha=1/255). But i like to have a full transparent background. How can i achieve this?

2.

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MagickSetImageBackgroundColor(image, color);
MagickBlurImageChannel(image, ChannelType.AllChannels, 0, 8);

with this result. This is what i want. Nice blur with transparent background. The problem here is that MagickSetImageBackgroundColor() does not have any influences. So how i can change the color here? (at another point i use MagickSetImageBackgroundColor() in combination with MagickShadowImage() which works fantastic)

Thanks for any advice!

Cheers,
Florian

[J2T]

Got it!

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MagickNewImage(coloredBG, width, height, color);
MagickBlurImageChannel(image, ChannelType.AllChannels, 0, 8);
MagickCompositeImage(coloredBG, image, CompositeOperator.CopyOpacityCompositeOp, 0, 0);

[el_supremo]

Don't know if this will work but try:

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MagickSetBackgroundColor(image, color);

instead of MagickSetImageBackgroundColor.

Pete
P.S. I see you've just got a solution. Try this anyway

[J2T]

No, that doesn't work either.

Thanks for your suggestions