I have three PIL images of the same size in RAM (no disk here). They represent different frequencies (details, shadow, mask).
Is it possible to overlay these images into a .xcf
file to further process them by hand in gimp? If so, can the opacity of the layers be controlled before saving the image?
I'm ideally looking for a python solution.
CodePudding user response:
Not certain what GIMP expects, but this might get you started as a multi-layer TIFF with varying opacities:
#!/usr/bin/env python3
import numpy as np
from PIL import Image
w, h = 400, 400
# Our layers to write to output file
layers = []
# Make layer 0 - 400x400 RGBA with red square, A=64
im = np.full((w,h,4), [0,0,0,64], np.uint8)
im[10:110, 10:110, :3] = [255,0,0]
layers.append(Image.fromarray(im))
# Make layer 1 - 400x400 RGBA with green square, A=128
im = np.full((w,h,4), [0,0,0,128], np.uint8)
im[20:120, 20:120, :3] = [0,255,0]
layers.append(Image.fromarray(im))
# Make layer 2 - 400x400 RGBA with blue square, A=192
im = np.full((w,h,4), [0,0,0,192], np.uint8)
im[30:130, 30:130, :3] = [0,0,255]
layers.append(Image.fromarray(im))
# Save as multi-layer TIFF with PIL
layers[0].save('result.tif', save_all=True, append_images=layers[1:], compression='tiff_lzw')
The Preview app on macOS displays it like this - hopefully you can see the red at least is more transparent, or less vibrant:
tiffinfo
perceives it like this:
TIFF Directory at offset 0x9740 (260c)
Image Width: 400 Image Length: 400
Bits/Sample: 8
Compression Scheme: LZW
Photometric Interpretation: RGB color
Extra Samples: 1<unassoc-alpha>
Samples/Pixel: 4
Rows/Strip: 40
Planar Configuration: single image plane
TIFF Directory at offset 0x20096 (4e80)
Image Width: 400 Image Length: 400
Bits/Sample: 8
Compression Scheme: LZW
Photometric Interpretation: RGB color
Extra Samples: 1<unassoc-alpha>
Samples/Pixel: 4
Rows/Strip: 40
Planar Configuration: single image plane
TIFF Directory at offset 0x30506 (772a)
Image Width: 400 Image Length: 400
Bits/Sample: 8
Compression Scheme: LZW
Photometric Interpretation: RGB color
Extra Samples: 1<unassoc-alpha>
Samples/Pixel: 4
Rows/Strip: 40
Planar Configuration: single image plane