TIFF Image Watermark saved as TIFF, file size reduction

Started 4 months ago | Questions thread
NAwlins Contrarian Veteran Member • Posts: 6,446
Re: Three factors affecting TIFF size

Thank you for this comprehensive reply!

You're welcome.

I follow the logic (I think!) - Is there a w/mark application that doesn't degrade the TIFF when applied?

I have no idea; I almost never watermark, and where I do, it's either in the raw converter (DxO PhotoLab has this feature) or pixel editor, basically part of the creation of the original file, not done with stand-alone watermarking software.

(I've just updated prior response with some image data, Pixels the same, one is uncompressed and 48 bit depth, the new watermark image is compressed "LZW" and a reduced bit depth of 24)

Yes, I saw where you wrote:

on reviewing "Properties"/"Details" for each image, original TIFF is noted as Uncompressed with a Bit Depth of 48, where as the watermarked image has compression noted as "LZW" (what is that??) and Bit Depth of 24.

which raises some issues. The bit depth of 48 means 16 bits for each of the red, green, and blue channels, and similarly 24 is 8 for each channel. If the file is a 16-bit uncompressed TIFF, and its size is 33 MB, then the image contains only about 5.8 megapixels. In other words, it had to have been heavily cropped and/or substantially resampled from the 6000x4000 pixels that the 80D captures to about 2940x1960 pixels before the first TIFF was created.

LZW is supposed to be lossless (see https://en.wikipedia.org/wiki/Lempel%E2%80%93Ziv%E2%80%93Welch). If you have about 2940x1960 pixels, for an 8-bit file that's 16.5 MB, from which a 7 MB file would be about 2.4:1 compression. Maybe on some images LZW can achieve the much compression. But even if some lossy compression was used, it should not be noticeably lossy. IOW, the quality should be excellent even if the compression is lossy.

So something is not making sense / is seriously off. Do you do so much watermarking that you have to use this software? Because at the moment I'm suspecting something is off with the watermarking software.

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