How pixel values are stored in CHDK raw?

PS

157
A610 1.00f

« on: 22 / January / 2010, 18:40:33 »

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Microfunguy

4037

Re: How pixel values are stored in CHDK raw?

« Reply #1 on: 22 / January / 2010, 18:55:02 »

« Last Edit: 23 / January / 2010, 08:32:53 by Microfunguy »

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reyalp

14082

Re: How pixel values are stored in CHDK raw?

« Reply #2 on: 22 / January / 2010, 23:49:31 »

This is how I got my head around how they are packed:
bytes is left to right, pixels is down, numbers are bits in the pixel value

Code: [Select]

	0      |1      |2      |3      |4      |5      |6      |7      |8      |9      |
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0   10      98765432                                                                
1     987654                3210                                                   
2   				543210      9876                                              
3   					  98                76543210                                
4   								98765432                10                      
5   												3210      987654                
6   													9876                543210  
7   																76543210      98

If you reverse the bytes, it makes more sense

EDIT: I.e. this is how it would be arranged in memory if it was big endian, which it isn't!

Code: [Select]

	0      |1      |2      |3      |4      |5      |6      |7      |8      |9      |
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0   9876543210                                                                      
1             9876543210                                                            
2   				    9876543210                                                  
3   				        	  9876543210                                        
4   								        9876543210                              
5   												  9876543210                    
6   												        	9876543210          
7   																      9876543210

Edit:
Newer cameras are 12 bpp

Code: [Select]

	0      |1      |2      |3      |4      |5      |
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0   3210    BA987654                                
1       BA98                76543210                
2   				BA987654                3210    
3   				                76543210    BA98

« Last Edit: 23 / January / 2010, 16:53:37 by reyalp »

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PS

157
A610 1.00f

Re: How pixel values are stored in CHDK raw?

« Reply #3 on: 23 / January / 2010, 14:36:21 »

So, is it 5B/4p or 10B/8p? Is this pattern correct?

00111111 00000000 11112222 22222233 33333333 44555555 44444444 55556666 66666677 77777777 ...

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reyalp

14082

Re: How pixel values are stored in CHDK raw?

« Reply #4 on: 23 / January / 2010, 17:00:26 »

Quote from: PS on 23 / January / 2010, 14:36:21

So, is it 5B/4p or 10B/8p? Is this pattern correct?

As above, on ten bit cameras it's 10 bytes / 8 pixels. On 12 bit cameras, it's 6 bytes / 4 pixels.

Quote

00111111 00000000 11112222 22222233 33333333 44555555 44444444 55556666 66666677 77777777 ...

This doesn't look right, see first diagram (past into something with a fixed font if it isn't showing up that way here). Or step through the read_pixel code.

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Microfunguy

4037

Re: How pixel values are stored in CHDK raw?

« Reply #5 on: 23 / January / 2010, 18:25:07 »

I worked this out some time ago but cannot guarantee it is correct :-

00111111 00000000 22222233 11112222 44444444 33333333 55556666 44555555 77777777 66666677

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