clothify makes extremely large png files!

[roncking@gmail.com]

Hi All, I'm using gimp 2.10 on a windows 10 box. When I clothify a 12mb png file, the exported png file is 378mb!
Why does this happen?

[rich2005]

(05-15-2023, 12:34 PM)roncking@gmail.com Wrote: Hi All, I'm using gimp 2.10 on a windows 10 box. When I clothify a 12mb png file, the exported png file is 378mb!
Why does this happen?

I can understand the file size increasing. This is a part of a 12.8 MB png file where the file size is 30 MB after clothify is applied and a re-export to png format.

   

Lots of "broken up" pixels that do not compress very well.

...but not 12 MB -> 378 MB Are you sure that is the correct size ?

Edit: I am assuming that you are using default png export settings with Compression = 9 (maximum)

[Ofnuts]

(05-15-2023, 12:34 PM)roncking@gmail.com Wrote: Hi All, I'm using gimp 2.10 on a windows 10 box. When I clothify a 12mb png file, the exported png file is 378mb!
Why does this happen?

What is the size of the image in pixels? Without compression, a 378MB file is roughly a 100Mpix image.

Also, if you promote the image to 32-bit FP on import, the export is by default a 16-bit PNG, so twice the size of the 8-bit PNG (so a 378MB would be a 50Mpx image).

[roncking@gmail.com]

The original image is 10,800 x 10,800 pixels 32-bit image. The image is of a person's face, very intricate colors. I'm exporting it compression level 9, automatic pixelformat.
Is there a way to export it smaller? I tried 16-bit rgb and it was still huge!

---

correction, the original is a 48-bit image

[Ofnuts]

No... The compression in PNG is essentially recognizing with very slow changes in color, and clothify does pretty much the opposite, by adding pixel-level detail. So you get no compression, and your final output is roughly the pixel count multiplied by 3,4,6,8, depends on number of channels and channel depth. 10800² × 4 = 466560000 = 445MB so you still get some compression...

[roncking@gmail.com]

Thanks for the info!

[rich2005]

(05-15-2023, 04:25 PM)roncking@gmail.com Wrote: The original image is 10,800 x 10,800 pixels 32-bit image. The image is of a person's face, very intricate colors. I'm exporting it compression level 9, automatic pixelformat.
Is there a way to export it smaller? I tried 16-bit rgb and it was still huge!

---

correction, the original is a 48-bit image

Original 48 bit ?  Is that 16 (red) + 16 (green) + 16 (blue) That is a 16 bit RGB.

Does the compression have to be lossless as with PNG ? A quick test with my clothified image and there was an advantage exporting to lossless webp format 

(no advantage using lossless jxl or near-lossless heif)