Batch changing picture files

[ChristinaChristina]

I'm trying to figure out how to make the following changes to all the files in folder c:....\input and save them to c:....\output.
I would really appreciate some help with what I should write as I am a complete newbie at this.
Also, I haven't figured out, should I write this in the command promt in C:\Program Files\ImageMagick-7.0.8-Q16\ or somewhere else?

Sourcefile is grayscale JPG.

* Change mode from grayscale to RGB.
* Add an alpha layer
* Convert all white to transparent
* Change black to red (or even better, if it is possible to get the program for each file to stop and ask me for which color to change to)
* Select a rectangle around the content (i.e. so that transparent area outside is excluded)
* Crop to selection
* Save as png

This is as far as I have gotten so far:
cd /users/me/input/
mogrify -strip -colorspace sRGB -format png -alpha set -fuzz 10% -transparent white ?????? -path /users/me/output/ *.png

[snibgo]

Change black to red

That would be:

Code: Select all

-fill Red -opaque Black

(or even better, if it is possible to get the program for each file to stop and ask me for which color to change to)

IM can't do that. Instead of mogrify, you could have a shell loop to process the files, with the shell asking the user for the colour.

Select a rectangle around the content (i.e. so that transparent area outside is excluded)
Crop to selection

I don't understand. Perhaps "-trim" or "-crop".

Sourcefile is grayscale JPG.

In that case, your mogrify command should end "*.jpg" not "*.png".

[ChristinaChristina]

Many thanks!

With the crop my thought was that I could crop away most of the empty/white area around the text which is written on the sheets that are scanned.

[fmw42]

use -fuzz XX% -trim +repage rather than -crop. See https://imagemagick.org/Usage/crop/#trim If the background color is constant, you can either remove the -fuzz XX% or use XX=0

[ChristinaChristina]

I will try that. Thanks!
Can I add a fuzz to the "-fill Red -opaque Black" in order to capture also the black that might have a hint of grey in it?

[snibgo]

Yes.

[ChristinaChristina]

Just realised that the same fuzz works for all colors so increased it to 30% and now it all works as a charm. Incredible!
Many thanks!
(I didn't work out how to handle the space in the folder names - but moved the files to a folder without space in the name

[fmw42]

Put your file names in double quotes if they have spaces in them

[ChristinaChristina]

(or even better, if it is possible to get the program for each file to stop and ask me for which color to change to)

IM can't do that. Instead of mogrify, you could have a shell loop to process the files, with the shell asking the user for the colour.

Can you suggest a good place to read up on how to use shell loops?

[fmw42]

I am not on Windows, but search Google for Windows .bat scripting for loops

[snibgo]

Can you suggest a good place to read up on how to use shell loops?

Type "help for" at the command line.