Legacy ImageMagick Discussions Archive

OK, I found the solution: use multiply:

magick convert 1.jpg -alpha set -channel A -evaluate multiply 0.50 +channel logo-just-transparent50pc-alpha.png

Hi, The PNG has some areas completely transparent and other areas fully opaque. I only want to have the opaque areas 50% transparent while keeping full transparency in the areas which are already fully transparent. This is what I do: magick in.png -alpha set -channel A -evaluate set 50% +channel out ...

Wow. That is incredibly efficient. I'm impressed.
thanks.

Thanks! Great explanations

Thank you!
Great!! What's the +channel at the end for?

Hi,

I want to transform any JPG into a 50% transparent PNG.
I found how to make a specific color fully transparent with:
But I don't want this: I want all the JPG to be a 50% opaque PNG.

Thanks

Thanks Fred for reporting this here. Much appreciated.

In some wild testing I found a voodoo workaround: using an odd number instead of an even number for -frame works! ie: 5 or 3 instead of 6.
Should be documented

My problem seems to be the same as this one reported 10 years ago but not followed through by original poster:
viewtopic.php?t=8427

Hello Fred, Thank you for your reply: much appreciated really. Yes: your demo works perfectly. My command also works for most files but not all: specifically some thin portrait-format photos generate the error. Output contact sheet: https://1drv.ms/i/s!AqDPqQIgWkb0zEZo6SK-RnBlHJj5 Original files ...

Hi, I am trying to create contact sheets with borders around the thumbnails. But the borders do not appear on all images. this is my command: magick montage -verbose -frame 6 -label "%%f" -font Arial -pointsize 10 -background "#ffffff" -fill "#333333" -define jpeg:size=200x200 -geometry 200x200+2+2 ...

Here is an example of what I mean http://prntscr.com/hql0yo On the left it is not good. I am expecting the frame to go all around the image, not leave a few pixels on the lower left side. On the right it's good: this is what I expect everywhere. Generated with -frame 6 -mattecolor "#eeeeee ...

Hi, Please look at this image from the imagemagick codex when doing a montage with both -frame and -label http://prntscr.com/he5lz8 Taken from here: http://www.imagemagick.org/Usage/montage/ The frame is missing pixels in the bottom left area: the label is overlapping the frame and removing these ...