SI2K downres maintain ability to debayer? at DVinfo.net

Justin Lovell · January 16th, 2011, 06:46 PM

I have si2k footage. shot 2048 x 1152
needs to be downconverted to 1920 x 1080 to be edited in FCP.

I downconvert the files, then lose the ability to debayer the new 1920x1080 files. I don't want to have to bake in the debayering during the downconvert.

Can HDLINK flag si2k footage so that debayering functionality is not lost when converting footage?

Mike McCarthy · January 19th, 2011, 11:09 PM

Debayering has to be performed before the image can be resized, so you cannot scale a "RAW" image and maintain its "RAW" status. Before debayering, the coordinates of an individual pixel imply information about its color information. Scaling the image before debayering would change these coordinates, and combine pixels of different colors, rendering the bayer pattern of color information useless. So basically the computer has to debayer the frame and generate all three color channels before they can each be scaled, so your 1920x1080 downres from the original SI2K file cannot be RAW.

This is why RED shoots a window mode in 2K, since the 4K image from the entire sensor cannot be scaled in RAW, the center crop is recorded pixel for pixel instead.

There are exceptions at certain ratios (1 in 9) which is how Canon DSLRs record low resolution (2MPixel) video frames from a high res (>18MPixel) bayer sensor without debayering each frame at full res when shooting video (Which is too processing intensive).

Kaspar Kallas · January 23rd, 2011, 09:54 AM

Hi

You can make (almost)arbitrary scale in bayer mode, just not by pixel skipping - what is an outrageously bad way of scaling a bitmap in a first place. But question here is can it be done in cinefrom with the cineform files originated from SI2K.

For the very same reason I finally gave up the fight for Years and went CS5 where scaling works in RT. What I would recommend (as long as FCP is not dealing with the problem) is like rewrap option there would be option to "crop" to FCP "legal" frame size. and once done in editing wrap it back for rendering.

In my most humble opinion.
-Kaspar

January 16th, 2011, 06:46 PM	#1
Justin Lovell Major Player Join Date: Feb 2009 Location: toronto, canada Posts: 212	SI2K downres maintain ability to debayer? I have si2k footage. shot 2048 x 1152 needs to be downconverted to 1920 x 1080 to be edited in FCP. I downconvert the files, then lose the ability to debayer the new 1920x1080 files. I don't want to have to bake in the debayering during the downconvert. Can HDLINK flag si2k footage so that debayering functionality is not lost when converting footage? __________________ Justin Lovell cinematographer//8mm.16mm>HD.transfers . www.framediscreet.com

January 19th, 2011, 11:09 PM	#2
Mike McCarthy Major Player Join Date: Oct 2007 Location: Northern California Posts: 517	Debayering has to be performed before the image can be resized, so you cannot scale a "RAW" image and maintain its "RAW" status. Before debayering, the coordinates of an individual pixel imply information about its color information. Scaling the image before debayering would change these coordinates, and combine pixels of different colors, rendering the bayer pattern of color information useless. So basically the computer has to debayer the frame and generate all three color channels before they can each be scaled, so your 1920x1080 downres from the original SI2K file cannot be RAW. This is why RED shoots a window mode in 2K, since the 4K image from the entire sensor cannot be scaled in RAW, the center crop is recorded pixel for pixel instead. There are exceptions at certain ratios (1 in 9) which is how Canon DSLRs record low resolution (2MPixel) video frames from a high res (>18MPixel) bayer sensor without debayering each frame at full res when shooting video (Which is too processing intensive). __________________ For more information on these topics, check out my tech website at www.hd4pc.com

January 23rd, 2011, 09:54 AM	#3
Kaspar Kallas Regular Crew Join Date: Oct 2007 Location: Estonia Posts: 142	Hi You can make (almost)arbitrary scale in bayer mode, just not by pixel skipping - what is an outrageously bad way of scaling a bitmap in a first place. But question here is can it be done in cinefrom with the cineform files originated from SI2K. For the very same reason I finally gave up the fight for Years and went CS5 where scaling works in RT. What I would recommend (as long as FCP is not dealing with the problem) is like rewrap option there would be option to "crop" to FCP "legal" frame size. and once done in editing wrap it back for rendering. In my most humble opinion. -Kaspar