Feature suggestion: .odc.thumbnail() method for generating and exporting low-res thumbnail images

[robbibt]

It would be very useful to have an easy .odc-accessible method for generating low-resolution thumbnail images, and exporting these to file:

It won't hurt to have something like .odc.compress(...., save_to="local/path/to/image.{png,jpeg,webp}"), or better a separate method like .odc.thumbnail() with some reasonable defaults for image output size with ability to override that, and maybe arguments like webmap=True|False for automatic conversion to epsg:3857? That method could then accept some form of output= argument supporting file, ram or fsspec.

...

Original question:

I'm trying to export a 320 x 320 pixel thumbnail to a compressed JPEG file on disk using odc-geo. I've been able to do the following, however I'm unsure of how to actually save the output of .odc.compress() as a file, not a string (?) representation.

(
    elevation.odc.reproject(
        how=elevation.odc.geobox.zoom_to(320), resampling="min"
    )
    .odc.colorize(vmin=-2.5, vmax=1.5, cmap="viridis")
    .odc.compress("jpeg", 85)
)

What do I need to do to save this output as a JPEG file on disk?

[Kirill888]

This can be viewed directly in jupyter with something like this:

from IPython.display import Image, display

display(Image(data=<...result of your code...>))

Or you can supply .odc.compress(..., as_data_url=True) and add result of that as an image overlay to a map or use in some HTML output of sorts.

There are no "save to disk" methods as such, it was developed for output to html mostly, with an assumption that the result takes a tiny fraction of the overall memory. One can always save bytes to a file obviously, something like this:

with open(output_path, "wb") as f:
  f.write(data)

But there are no arguments or methods to do that within odc.geo currently. Or maybe you want to use fsspec and write to a zip file or S3 bucket or embed data url into a STAC document.

It won't hurt to have something like .odc.compress(...., save_to="local/path/to/image.{png,jpeg,webp}"), or better a separate method like .odc.thumbnail() with some reasonable defaults for image output size with ability to override that, and maybe arguments like webmap=True|False for automatic conversion to epsg:3857? That method could then accept some form of output= argument supporting file, ram or fsspec.

[robbibt]

Ah, this was all I was looking for, thanks:

with open(output_path, "wb") as f:
  f.write(data)

I think an .odc.thumbnail or .odc.write_thumbnail method would be super useful - it's a super common use case that is currently a bit clunkier than it needs to be. I'll update this issue.