Error saving a demosaiced image: "Cannot handle this data type: (1, 1, 3), <f4"

[alessandrofrancesconi]

I'm trying to demosaic a BMP image based on "GRBG" Bayer pattern, this way:

img = colour.io.read_image("input.bmp")
coloured = demosaicing_CFA_Bayer_bilinear(img, "GRBG")
encoded = colour.cctf_encoding(coloured)
colour.io.write_image(encoded, "result.bmp")

But write_image throws Cannot handle this data type: (1, 1, 3), <f4

To be noted, the program shows this warning at the beginning: ColourUsageWarning: "OpenImageIO" related API features are not available, switching to "Imageio"!

If useful, this is the input image: input.zip

Can you help me? Thanks!

[alessandrofrancesconi]

After installing OpenImageIO, it worked. Anyway, I'm wondering what could be the issue with Imageio.

[KelSolaar]

Hi @alessandrofrancesconi,

We always convert the image type to float32 and normalise it between [0, 1] if it is of an integer type:

>>> colour.io.read_image_Imageio("/Users/kelsolaar/Downloads/input.bmp").dtype
dtype('float32')

When it come to writing, Imageio is not as smart as OpenImageIO and tries to write that float32 data into a 8-bit Bitmap container, so it fails.

Hope that makes sense!

Cheers,

Thomas