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Error adding mask as alpha channel
See original GitHub issueIssue Description
Problem
Calling array_to_image using the array and mask returned from tile using a 4 band tiff returns an error: WEBP driver doesn't support 5 bands. Must be 3 (RGB) or 4 (RGBA) bands.
Relevant code
# image at URL is 4 band geotiff
tile, mask = main.tile(url, int(tile_x), int(tile_y), int(tile_z), tilesize=256, nodata=None)
options = img_profiles["webp"]
buffer = utils.array_to_image(tile, mask=mask, img_format="webp", color_map=None, **options)
Possible Cause
It looks like utils:392 is just adding a band to the array without checking to see whether an alpha band already exists
Issue Analytics
- State:
- Created 4 years ago
- Comments:9 (5 by maintainers)
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@vincentsarago Yes we implemented additional check’s for 4 band images and handle them differently. I think the older version of
array_to_imgused ahas_alphacheck, was that specific to PIL support?👋 @a2hill sorry for this
bugI don’t see a fix directly to thearray_to_imagefunction but to me it seems you could passindexes=(1,2,3)to themain.tilefunction and then the mask return should be the alpha band.Handling nodata/mask/alpha band is a tricky thing (I’ve worked on the matter all the week), maybe
utils.tile_readcould remove the alpha band from thedataarray directly ?Edits:
Here you are also passing the
maskto the function, but the alpha band is already provided with your data, so you have two solution:indexes=(1,2,3)maskto theutils.array_to_imagefunction