Legacy ImageMagick Discussions Archive

Apologies for tacking onto the thread - the symptoms were the same so I thought it was relevant.

And thanks for pointing out my incorrect PNG output syntax.

Photoshop PSD file:
https://www.dropbox.com/s/3h0d0q1aslr1m13/move_oolong.psd

Composite (layer 0):
https://www.dropbox.com/s/dyobhg1rhf4qj37/move_oolong_composite_from_7.0.8.14.png

Layer 9 (7.0.8.30/32/39/40 beta) - broken?
https://www.dropbox.com/s/f026ic3rwcisqhd/move_oolong_layer_9_from_7 ...

I'm having the same exact problem, except with Photoshop PSD files. If I tell it to extract all layers to PNG, I get the individual layer images, but if I target a specific layer it renders black.

I tested both 7.0.8-32 and latest 7.0.8-39 64-bit releases on Windows 10 (ImageMagick-7.0.8-32-Q16-x64 ...

Apologies for the invalid command. I meant to use this for determining the bounding box:
Thanks for the recommended approach!

I want to determine the best/fastest way to detect if an image is entirely blank (assume image has alpha channel).

Test image https://www.dropbox.com/s/46zdazxrgy83gmc/empty.png?dl=0

Possible approaches:

1. Check for mean of zero (or standard deviation of zero?)
identify -format "%[opaque ...

Thanks, that was the piece I was missing. I was hoping I could perform the modulation in CMYK in order to emulate a workflow from Photoshop, where this is possible. This particular workflow does a lot in CMYK mode and I was hoping to avoid a lot of CMYK -> sRGB -> CMYK conversions.

I'm trying to do a simple saturation bump on a CMYK image. I'm starting with a PNG image containing an embedded Adobe RGB profile, convert to CMYK with a provided color profile, then modulate the saturation by 20%:


convert sample.png -profile USWebCoatedSWOP.icc sample_CMYK.tif
convert sample ...

I've looked at following posts for reference:

"Combining multichannel images" http://imagemagick.org/discourse-server/viewtopic.php?t=21159
"Combining Channel Images with custom colors" http://imagemagick.org/discourse-server/viewtopic.php?t=28146

The first post is closest to what I need. In ...

Ah. I assumed the channel names should have corresponded to those provided by "-list channel". (The docs do suggest this: "To print a complete list of channel types, use -list channel."). But I see they are explicitly not valid '-channel' inputs per the docs.

Thank you for the clarification.

Converting an sRGB PNG file to LAB colorspace before separating channels works fine; however if I attempt to limit it to a specific LAB channel the output is inconsistent. (I get the same results if I start with a LAB colorspace TIFF and don't perform any colorspace conversion.)

magick foo.png ...