Huge File from Gigapixel -> Jpeg-2-RAW

Starting with a JPEG with the dimensions and size: 1920x1080 656KB

GigaPixel AI @ 6x = 11520x6480 52MB

So far seems about right.

JPEG-2-RAE DNG = 256x144 427MB

Whoa. 427MB DNG file? And what’s with the tiny dimensions.

Rather new to this, so maybe I am missing something, but I cannot understand how a 52MB JPEG can become a 427MB RAW File.

All thoughts and opinions appreciated.

I suspect that the JPEG file is not 256 x 144 as, in my case just now, a 600 x 400 JPG becomes 1.62MB DNG after being passed through JPEG to RAW.


Upload your input image to a file sharing site, post the link here, and someone will look at it.

I am not so concerned with the file dimensions as the fact that a 52MB JPEG becomes a 427MB RAW file, over 8 times the original size of the image.

I would think that is a reasonable size for a 11520 x 6480 image. Which is 74, 649, 600 pixels, but check by raising a support request at the main website to confirm this. You should also remember the actual size of a JPEG depends on the quality it was saved as.

That is exactly the result that should be expected.

Firstly, the Windows file sizes for the JPG’s are compressed and are not relevant as such. The important size is the uncompressed size of the image.

So the uncompressed size of a 1920px by 1080px 24 bit (8 bit/channel) RGB image is 5.93MB.
After upsizing this by 6 in Gigapixel, it become a 11,520px by 6480px 24bit (8 bit/channel) JPG image with an uncompressed size of 213.6MB.

Now when you convert that JPG to DNG in JPG to RAW AI, it remains as a 11,520px by 6480px image, but it has been converted in the process from a 24 bit image to a 48 bit image, so the uncompressed size becomes 427.1MB, and that file is being saved without compression.

You can simply calculate the uncompressed size of an image using the following:

Width (px) x Height (px) x Bit Depth = bits.
Bits/8 = Bytes
Bytes/1024 = Kilobytes
Kilobytes/1024 = Megabytes.

In the above the Bit Depth for the JPG’s is 24 (8bit each R, G B channels)
For the DNG “Raw file” the bit depth is 48 (16 bit each for R, G and B)

Hope that helps