Size variances in PS

[David Eckels]

When I look at the size of a DNG image file in LR, it is 38 Mb. When I open it in PS, it goes to 260 Mb. Even converting to an 8-bit file, it is at 130 Mb. This is without any modification (ie, no additional layers). What gives?

[digitaldog]

Assuming the DNG contains raw data, it's not rendered and further, DNG has compression.

[David Eckels]

Thanks, Andrew, yes raw files. But I also checked an old D800 NEF and it goes from 44 MB to 207 MB when opened in PS. There must be a reference on this somewhere, eh?

Did some math. D800 NEF 7360 x 5912 pixels at 16 bits per pixel is 696,197,120 bits. Convert to 8-bit bytes and I get 87,024,640 bytes or just under 85 MB. Can there be over 100 MB of extra info when rendered?

PS I do use lossless compression, but that shouldn't alter my math assumptions. But you know what they say about assume...
     I also realize that I am saving 14-bit NEF to the card.

[fdisilvestro]

Did some math. D800 NEF 7360 x 5912 pixels at 16 bits per pixel is 696,197,120 bits. Convert to 8-bit bytes and I get 87,024,640 bytes or just under 85 MB. Can there be over 100 MB of extra info when rendered?

When you render, you have that amount of information for every channel (RGB), so you still have to multiply by 3