EPisch
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Posts: 19
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« Reply #4 on: July 24, 2024, 12:16:36 PM » |
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To tell you the truth: No, I haven't :-( I haven't used LZW for a long time because it delays saving and often produces larger files than the uncompressed image file. But your idea is a good one and that is why I have now carried out further investigations. I have tested different file formats using two different photos. The first photo contains a lot of detail, which makes efficient compression more difficult. The second photo shows a blue sky with a few clouds, which should be very easy to compress.
Here are the results:
Grainy wall with detailed wooden door size [KB] size [%] (6176x8858px) TIFF 16bit uncompressed 320615 100,00 TIFF 16bit LZW 416507 129,91 TIFF 16bit ZIP 315873 98,52 PNG 16bit fast 270140 84,26 PNG 16bit medium 270135 84,26 PNG 16bit small 269503 84,06 JXL 16bit lossless 208481 65,03 <<< JXL 16bit quality 100 24279 7,57 JXL 8bit transcode from JPEG 31055 9,69 JPEG 8bit 37303 11,63
Cloudy sky (9504x6336px) TIFF 16bit uncompressed 352901 100,00 TIFF 16bit LZW 399351 113,16 TIFF 16bit ZIP 325475 92,23 PNG 16bit fast 249114 70,59 PNG 16bit medium 242573 68,74 PNG 16bit small 242539 68,73 JXL 16bit lossless 177324 50,25 <<< JXL 16bit quality 100 3903 1,11 JXL 8bit transcode from JPEG 8347 2,37 JPEG 8bit 10269 2,91
For both images, the LZW TIFF file saved with Photoshop was larger than the uncompressed TIFF file. I got the same result when saving with Affinity Photo. "JXL 8bit transcode from JPEG” means the following: JXL allows a lossless conversion from JPEG to JXL. That means, that the already lossy information of the JPEG will not lose more details by converting it to JPEG XL. But the resulting file is only slightly smaller than the JPEG file. “JXL 16bit quality 100” is the storage method I tested with Affinity Photo. Although this is not lossless, I could not detect any visual differences to the original - not even when overlaying in Photoshops layers using “Difference” at 100% view. This extreme compression rate is still somewhat suspect to me and I would not yet trust it completely. But even the lossless compression is significantly better than with all other file formats. And as I have already checked, color profiles are also supported. Best regards, Ernst
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