Trying to understand RAW file formats

R
Posted By
Roger
May 29, 2008
Views
332
Replies
2
Status
Closed
I am struggling, trying to understand the format of RAW files. I understand that there is a luminosity channel (12 or 14 bits, depending on the camera) for each pixel which accounts for the bulk of the information, plus color information(???).

Here I thought there would just be three 12-bit (or 14 bit) for each color channel but, for an 8 MP camera, this would result in a 36MB (1.5 bytes * 3 * 8 *10^6) file which is certainly not the case (even considering benefit from any loss-less compression). How can Canon fit an 8MP color RAW image into an ~8MB file? Are there really only 8MB/3 = 2.67MP (real, multi-colored MP’s) from a "8MP" camera such as the 20D or 30D?

Master Retouching Hair

Learn how to rescue details, remove flyaways, add volume, and enhance the definition of hair in any photo. We break down every tool and technique in Photoshop to get picture-perfect hair, every time.

T
Tak
May 29, 2008
"Roger" wrote in message
I am struggling, trying to understand the format of RAW files. I understand that there is a luminosity channel (12 or 14 bits, depending on the camera) for each pixel which accounts for the bulk of the information, plus color information(???).

Here I thought there would just be three 12-bit (or 14 bit) for each color channel but, for an 8 MP camera, this would result in a 36MB (1.5 bytes * 3 * 8 *10^6) file which is certainly not the case (even considering benefit from any loss-less compression). How can Canon fit an 8MP color RAW image into an ~8MB file? Are there really only 8MB/3 = 2.67MP (real, multi-colored MP’s) from a "8MP" camera such as the 20D or 30D?

In most sensors each pixel is one of a red, green, or blue. They are are arranged in a matrix using some pattern. When the RAW file is processed an interpolation takes place between neighboring pixels such that the result is pixels which are tri-color, and usually of 8 bits per color.

See the wikipedia article here:

http://en.wikipedia.org/wiki/Color_filter_array

I think most sensors use the Bayer matrix.
JS
Jonas Siebert
Jun 5, 2008
Roger schrieb:
I am struggling, trying to understand the format of RAW files. I understand that there is a luminosity channel (12 or 14 bits, depending on the camera) for each pixel which accounts for the bulk of the information, plus color information(???).

Here I thought there would just be three 12-bit (or 14 bit) for each color channel but, for an 8 MP camera, this would result in a 36MB (1.5 bytes * 3 * 8 *10^6) file which is certainly not the case (even considering benefit from any loss-less compression). How can Canon fit an 8MP color RAW image into an ~8MB file? Are there really only 8MB/3 = 2.67MP (real, multi-colored MP’s) from a "8MP" camera such as the 20D or 30D?

thats out of my imagination….

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

Related Discussion Topics

Nice and short text about related topics in discussion sections