Legacy ImageMagick Discussions Archive

Hello,

I'm having trouble converting a vector file to PNG while preserving alpha transparency. I've tried every possible combination of options I could find on the board, and still no luck.

I've tried starting with all 3 of these file types:

• EPS: http://banjo.brighterplanet.com/andy/motorcycle.eps
• PDF: http://banjo.brighterplanet.com/andy/motorcycle.pdf
• SVG: http://banjo.brighterplanet.com/andy/motorcycle.svg

The EPS and PDF always come out with a white background, despite trying the "-colorspace RGB," "-channel RGBA," and "-background none" tricks I have found here.

Here are some examples:

• convert -channel RGBA -colorspace RGB motorcycle.eps motorcycle-1.png
• convert motorcycle.eps -channel rgba -alpha On -background transparent motorcycle-2.png
• convert -background none motorcycle.eps -channel rgba -alpha On -background transparent motorcycle-3.png
• convert -background none motorcycle.pdf -background transparent -alpha On motorcycle-4.png
• convert -background none motorcycle.svg -background transparent -alpha On motorcycle.png

The closest I'm getting is with the SVG, but the resulting PNG inexplicably has a black background with 50% transparency behind the motorcycle.

Thanks in advance.

Type

• convert -colorspace RGB motorcycle.eps motorcycle.png
  identify -verbose motorcycle.png

We get alpha statistics that show levels of transparency:

• alpha:
  min: 53713 (0.819608)
  max: 65535 (1)
  mean: 65525.1 (0.999848)
  standard deviation: 301.241 (0.00459664)
  kurtosis: 1034.93
  skewness: 31.6121

Do you get the same distribution for alpha?

Full output is at http://pastie.org/484496

It appears that the conversion from EPS to PNG is preserving transparency as expected.

Thanks for helping me with this!

Unfortunately, here's the output image that resulted from the commands you had me run:


http://banjo.brighterplanet.com/andy/motorcycle.png

As far as I can tell, it's not transparent.

For comparison, when I use Illustrator's Save for Web, I get this:


http://banjo.brighterplanet.com/andy/mo ... narrow.png

If the image is not rendered correctly, the bug is in Ghostscript or the Ghostscript pngalpha device. ImageMagick delegates Postscript rendering to Ghostscript with this command line:

• "gs" -q -dQUIET -dPARANOIDSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dAlignToPixels=0 -dGridFitTT=0 "-sDEVICE=pngalpha" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-r72x72" -g121x87 "-sOutputFile=/tmp/magick-XX1HoH3Z" "-f/tmp/magick-XXlMwZ7j" "-f/tmp/magick-XXBA8lcE"

Any chance you could try that convert command on motorcycle.eps and make sure I'm not just crazy?

Thanks again.

I downloaded your motorcycle.eps and did the following on IM 6.5.4-7 Q16 Mac OSX Tiger (with gs 8.61) and got:

convert motorcycle.eps motorcycle.png
Unknown device: bmpsep8
Unrecoverable error: undefined in .uninstallpagedevice
Operand stack:
defaultdevice
Unknown device: bmpsep8
Unrecoverable error: undefined in .uninstallpagedevice
Operand stack:
defaultdevice
convert: Postscript delegate failed `/var/tmp/magick-DWKZZyaR': No such file or directory @ ps.c/ReadPSImage/741.
convert: motorcycle.eps: invalid TIFF directory; tags are not sorted in ascending order. `TIFFReadDirectory' @ tiff.c/TIFFWarnings/525.

But it produces a partially transparent image:


But if I do
convert -colorspace rgb motorcycle.eps motorcycle2.png

I get a white background:

Interesting. Dropping the colorspace argument like you did in your first test results in a white background for me, but runs without errors.

Does anybody have a test EPS with alpha transparency that has been verified to produce a correct PNG? I'd love to try it on my machine.

I had this same problem/error in viewtopic.php?f=1&t=13753&hilit=bmpsep8 and viewtopic.php?f=3&t=13723&p=46762&hilit=bmpsep8#p46762

but so far no one has told me how to correct or avoid that error message. There must be some configuration that I need to do to fix it. Perhaps a GS upgrade. But I don't know for sure.

For any Googlers landing here: rsvg performs SVG -> PNG-24 (with alpha transparency) conversions flawlessly.

Use this command to perform SVG -> PNG-24 (with alpha transparency) conversions flawlessly:

• convert -background none motorcycle.svg motorcycle.png

Not sure why it did not work for you. We're using ImageMagick 6.5.2-7, the current release.

Unfortunately, this is what I get from that command:


http://banjo.brighterplanet.com/andy/motorcycle-12.png