Does IMage::write_to_tofile implicitly convert to sRGB? #4130
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Hello @CoachRDeveloper, Yes, the savers will implicitly convert the image to one of the formats supported by the image type. So (for example) the jpeg saver will convert to one of: one band mono, three band RGB, or four band CMYK, all of then 8 bit depth. For your code, try (python for brevity): img = img.colourspace("lab")
img *= [1, 1.3, 1.3]
img.write_to_file("xx.jpg")
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Thanks about confirming the behavior of the write. May be something that is worth to be added to the documentation? I know about the LABQ issue. That was mentioned by you in another discussion (and according to previous comments, to be fixed in 8.16). I did not use LABQ, but LABS (VipsInterpretation::VIPS_INTERPRETATION_LABS). I wonder whether I did something wrong in my C++ code about lineair. According your python example (I'm not familiar with it) it looks about the same. According to the documentation, img.linear multiplies double a to the image and add b. That's probably my mistake. I have changed my code to: |
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I discovered that writing a vips image in LABS colorspace to disk produces same output as when first a convert to sRGB is done. Does this mean that VIMage::write_to_tofile() implicitly converts an image to sRGB?
I've checked vips_foreign_find_save and vips_image_write_to_file, but did not find information about that.
I'm not very familiar to the JPEG format, but according Wiki the color space can be written to the file (remembering things about sRGB vs Adobe RGB when printing photos).
Actually, the code behind this question is how to adjust saturation. Borrowed from another example I created some code like this (thanks to another piece of information, that direct convert to LABS is not possible):
Actually two questions:
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