Legacy ImageMagick Discussions Archive

Hi,

I need to make crops in identical places to a number of images WITHOUT destroying the originals. The -write option to convert takes a filename argument, "-write filename". This would seem to have zero ambiguity as written.

Convert a specified image by cropping it to a given geometry (size and starting XY) and write the output to a different filename. A complete logical process, a complete sentence, a complete, fully specified command. Just what is needed.

There is an error which seems to make no sense since the crop is done as specified (after hitting the F5 key to refresh windoz exlorer). I make it a point to check return codes and the $ERR string in PerlMagick after such operations.

The command line:
>"c:\Program Files\ImageMagick-6.8.9-Q16\convert.exe" tl-2014.0416-215799.p1.pristine.jpg -crop 2100x1300+5400+2900 -write 215799.zero.crop.jpg
convert.exe: missing an image filename `215799.p1.zero.crop.jpg' @ error/convert.c/ConvertImageCommand/3184.

The convert command line seems to follow the web documentation to the letter. The output image is just what is asked for. The error message appears to be completely out of line because the -write <<FILENAME>> is given, understood and used BY CONVERT as intended. Then it squawks about not having the exact filename it just read and used correctly.

Is it necessary to just keep a running of list of errors that are not really errors so they can be safely ignored? Or, am I missing a subtlety in the convert command?

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    $err = $CONVERT_COMMAND;
    if($err  &&  $err =~ m/missing an image filename .*$crop_name.*convert.c)  {
        if(-f $crop_name)  {
            # Ignore totally Bo-o-o-gus error. Crop done, file written.
        }
        else  {
            &FREAK_OUT_CROP_REALLY_FAILED_THIS_TIME();  #
       }
    }

Bizarre,
Brian

From http://www.imagemagick.org/script/comma ... .php#write
-write filename write an image sequence;
The image sequence preceding the -write filename option is written out, and processing continues with the same image in its current state if there are additional options ...

Version: ImageMagick 6.8.9-2 Q16 x64 2014-05-27
win7/64

BrianP007 wrote:Or, am I missing a subtlety in the convert command?

Yes.

The minimum convert syntax is:

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convert input-image output-image

You can put lots of extra stuff before or after the input-image. You can't put anything after the output-image.

One of the extra stuff you can use, if you want, is "-write filename".

So, you can probably see the problem now. You don't have an output-image. If you remove "-write", it should work.

You can use multiple -write filenames each in its own parenthesis with its own set of options and then just put null: for the final output.

windows syntax (I think):

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convert input ^
( -clone 0 <options> -write filename1 +delete ) ^
( -clone 0 <options> -write filename1 +delete ) ^
... etc ...
( -clone 0 <options> -write filenameN +delete ) ^
null:

The null: is needed to remove the input from memory (discard it). The +deletes get ride of each clone after writing the processed result to disk.

Yes. So a different way of fixing Brian's command is by adding "NULL:" to the end, as the output-image:

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"c:\Program Files\ImageMagick-6.8.9-Q16\convert.exe" tl-2014.0416-215799.p1.pristine.jpg -crop 2100x1300+5400+2900 -write 215799.zero.crop.jpg NULL:

As a general rule, I do this only for cases like Fred's where the command isn't really creating a single output.

snibgo wrote:As a general rule, I do this only for cases like Fred's where the command isn't really creating a single output.

I would agree. I don't often use this technique either.

OK. I see the pattern. And it explains the error message.
convert INPUT_FILE [options ... ] OUTPUT_FILE <enter>
...
Option `-WRITE filename` may be used to write intermediate results as the command is executed in chunks!
Very handy.
The output_file was being absorbed by the option -write leaving the second and last MANDATORY arg empty. And, it did the right thing, produce the crop, with the information that it had rather than just die with a cryptic message (bad command or file name) because something wasn't perfect. Robust!

>> "The ImageMagick command line can be as simple as this. $ convert image.jpg image.png " is the link I missed! D'oh!

I just did not want to always dump STDERR > /dev/null as was tempting to do or write kludgy code for it.

Yes, that's it.

Slightly confusingly, the inputs and and outputs don't have to be images or files. This is fine:

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convert xc: info:

It makes an image with a single white pixel, then writes text information about it.

Legacy ImageMagick Discussions Archive

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convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??

Re: convert in_file -crop $GEOM -write output_file -> Error missing output_file??