Build thumbnail images driving darktable 4.2 with lua

Software darktable
1

Hello,
I have looked at the various lua scripts available. All the scripts seem to use ImageMagick to build thumbnail images.
I’m trying to build a lua script to generate web album.
I was wondering if you can export images from darktable via lua in webp format for example in different sizes.

2

That should be possible, yes.

3

You can export files in any format supported by the exporter (with the exception of jxl?). See darktable lua documentation - types

4

While trying to implement a widget I notice none of the existing module with a widget seem to work.
For example ‘selection_to_pdf’ should activate a widget in the lighttable view but none is displayed when activating via script manager.
I’m using the macos version with darktable version 4.2.0.

5

selection_to_pdf adds an entry to the target storage drop down of the export module. Just tested on Linux and it works fine.

6

You’re right. Sorry for the noise.

7

I’ve made big progress. This code allows me to produce images of different sizes.

wa.exporter = dt.new_format(“jpeg”)
wa.exporter.quality = 80
wa.exporter.max_height = max_height
wa.exporter.max_width = max_width
wa.exporter:write_image(image, export_file)

I need to get back the exact size of the image that was produced.
This image is no longer in darktable.
Can I use a darktable function to get information on that image ?