selmslie Loc: Fernandina Beach, FL, USA

Some editors insist on a 48-bit color image, even if you have converted your image to B&W. Since all three color channels contain the same information this seems to be a waste of space. But if your editor can support a 16-bit grayscale you can save some of that space.

The attached image was taken as a 3436x2648 Dx crop (10.4 MP) on a 24 MP sensor and developed from raw. If you click the Download link it may download to you computer rather than opening the image in your browser.


(1) from Picture Window Pro
(2) from Affinity

At 10.4 MP you might expect that the TIFF would have a minimum size of 20.8 MP. I cannot account for the missing bytes.

I used this crop so that I could actually post the 16-bit TIFF here.

16-bit grayscale image

(Download)

rmcgarry331

Tiff file size for 16 bit grayscale 3436x2648x2= 18,197,056 bytes, or 17.77 mb. It is likely LZW compression is turned on, which would compress the file down to 17.51 mb.

selmslie Loc: Fernandina Beach, FL, USA

Thanks for the info. I guess PWP compressed it some and Affinity compressed it again.

I'll try to see if I can set it to no compression although it doesn't seem to have lost anything.

selmslie Loc: Fernandina Beach, FL, USA

After looking at it again the numbers are slightly different. I changed the values to kilobytes to be more precise.


(1) from Picture Window Pro
(2) from Affinity

The 48-bit tiff is 3x as large as the 16-bit version as expected. I don't recall where the other number came from because I erased the first results and did it all over.

Neither PWP not Affinity refer to LZW compression explicitly but it's clear that Affinity is doing more compression than PWP.

With PS Elements I could specify whether to use no compression or LZW compression. With no compression the file size is about the same as the PWP result.