问题
Brief:
convert ( -size 585x128 gradient: ) NewImage.png
How do I change the above ImageMagick command so it takes the width and height from an existing image? I need it to remain a one line command.
Details:
I'm trying to programatically create an image reflection using ImageMagick. The effect I am looking for is similar to what you would see when looking at an object on the edge of a pool of water. There is a pretty good thread on what I am trying to do here but the solution isn't exactly what I am looking for. Since I will be calling ImageMagick from a C#.Net application I want to use one call without any temp files and return the image through stdout. So far I have this...
convert OriginalImage.png ( OriginalImage.png -flip -blur 3x5 \
-crop 100%%x30%%+0+0 -negate -evaluate multiply 0.3 \
-negate ( -size 585x128 gradient: ) +matte -compose copy_opacity -composite )
-append NewImage.png
This works ok but doesn't give me the exact fade I am looking for. Instead of a nice solid fade from top to bottom it is giving me a fade from top left to bottom right. I added the (-negate -evaluate multiply 0.3 -negate) section in to lighten it up a bit more since I wasn't getting the fade I wanted. I also don't want to have to hard code in the size of the image when creating the gradient ( -size 585x128 gradient: ) I'm also going to want to keep the original image's transparency if possible.
To go to stdout I plan on replacing "NewImage.png" with "-"
回答1:
If you are calling it from C#, perhaps you could get retrieve the image dimensions in C#. Then call the ImageMagick command with
command = String.Format("convert bar %1x%2",img.Width,img.Height)
回答2:
You should take the existing image as an input, and create the gradient yourself using -fx instead of using the gradient pseudo-format.
回答3:
May be this can help: Reflection under an image
#!/bin/sh
gamma=$1
source=$2
destination=$3
size=`identify -format "%wx%h" $source`
convert $source \
\( -size $size xc:none \
\( \( -flip $source -crop $size+0+0 \) \
-size $size gradient: -gamma $gamma \
-compose copy_opacity -composite \) \
-compose blend -composite \) \
-append $destination
来源：https://stackoverflow.com/questions/198928/imagemagick-reflection