Thumbnail flag in resize causes: no decode delegate for this

[Exception e]

I have the problem that adding a -thumbnail flag to a resize command gives no decode delegate for this image format.
Resize without -thumbnail just works. Why this difference?


This works

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FOR %%G IN (*.jpg) DO (
    D:\progs\ImageMagick\convert.exe %%G -interlace plane -quality 85 "84x53>" -resize ..\thumbs\%%G 
)

This works not:

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FOR %%G IN (*.jpg) DO (
    D:\progs\ImageMagick\convert.exe %%G -interlace plane -quality 85 -thumbnail "84x53>" ..\thumbs\%%G 
)

it gives:

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convert.exe: no decode delegate for this image format `C:/DOCUME~1/Erich/LOCALS~1/
Temp/magick-jzTjvk2f' @ constitute.c/ReadImage/531.

Those magick-* files are 0bytes and do not have an extension.


I have the stand-alone version of ImageMagick, on windows xp32 sp3. Imagemagick is not in the path, nor do I have any special imagemagick environment variable defined.

Some info from identify -list format:

JNG* rw- JPEG Network Graphics
See http://www.libpng.org/pub/mng/ for details about the JNG
format.
JP2* rw- JPEG-2000 File Format Syntax
JPC* rw- JPEG-2000 Code Stream Syntax
JPEG* rw- Joint Photographic Experts Group JFIF format (70)
JPG* rw- Joint Photographic Experts Group JFIF format (70)
JPX* rw- JPEG-2000 File Format Syntax

edit: corrected the examples, missing input parameter due to wrong copying here.

[el_supremo]

I don't see how your first command can work because it has "84x53>" without a preceeding operation (-resize ??) and the convert command also requires an input and output filename whereas your command only has one filename. Both commands, as you have shown them, should fail.

Pete

[Exception e]

Pete thanks, you were right that -resize was missing in the first example.

The mad thing is: it correctly thumbnailed the jpgs (the size is correct at least). So I do not understand what went wrong.

I've changed the parameter order. Is this correct? It runs at least.

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D:\progs\ImageMagick\convert.exe %%G -thumbnail  "84x53>" -interlace plane -quality 85  ..\thumbs\%%G 

Some 0-byte files get this warning, but the error disappeared at least.

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convert.exe: Empty input file `102657.jpg' @ jpeg.c/EmitMessage/233.
convert.exe: missing an image filename `..\400-400\102657.jpg' @ convert.c/Conve
rtImageCommand/2838.

[el_supremo]

The command looks good now. You could use the DOS "if" command to test for a zero length file but either way it's best ot have something warning you of bad files.

Pete