Color conversion

[aabacchus]

I often scan some work and want to convert the images to a pdf for uploading.
These images can be very large in size but I can "remove" the color from them by converting the pdf to grayscale, and this can vastly reduce the file sizes, usually by about 10 times.

At the moment I use Ghostscript in this way:

#!/bin/sh
gs      -sOutputFile=gray.pdf \
        -sDEVICE=pdfwrite \
        -sColorConversionStrategy=Gray \
        -dProcessColorModel=/DeviceGray \
        -dCompatibilityLevel=1.4 \
        -dNOPAUSE \
        -dBATCH \
        $1

Could a similar feature be implemented in pdfcpu?

[hhrutter]

Hello!
Can you share a small sample input PDF for analysis?

[aabacchus]

Here's a jpg photo of a page of work:
Taken pretty hurriedly, lighting is yellow, there's a bit of my table in the background.
It's 3.3M.

Converted to a pdf using pdfcpu import sample-pic.pdf sample-pic.jpg: sample-pic.pdf
Also 3.3M.

Now running the above script: gray.pdf
Size is 420k and no distracting colour.

[hhrutter]

I'll check it out 👍
Thank you for using pdfcpu 💚

[hhrutter]

Fixed with the latest commit!

Now you can do: pdfcpu import -- "gray:true" gray.pdf test.jpg to get what you need.