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by blindbloom
Mon Jul 10, 2017 4:48 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

This is the typical result of performing demosaic only. The sensor values are linear with respect to scene radiance (aka scene-referred), which accounts for the dark appearance. A raw processing pipeline (e.g. David Coffin's dcraw) applies additional color processing to put the image into an output-...
by blindbloom
Tue Jul 19, 2016 9:00 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Yes, in principle I agree with you, but forums are, by nature, notorious for digressions and bifurcations. Nevertheless, I will be more mindful of your guidelines in the future. Thank you for pointing this out.
by blindbloom
Tue Jul 19, 2016 6:37 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Very helpful. Thank you so much!
by blindbloom
Tue Jul 19, 2016 5:39 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I have a couple questions about RAW output behavior, and since this thread is titled "Raw Output Information" it seems like a great place for me to learn from others who are willing to share their knowledge and experience. I am wondering about heat-related issues when taking RAW images with long exp...
by blindbloom
Mon Jul 18, 2016 4:29 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I am also interested in long exposures and have heard that this leads to heat problems. Is that true? If so, does that lead to more noise? Does it lead to permanent H/W damage?
by blindbloom
Tue Dec 15, 2015 6:19 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Schwabenchris provided two DNG files: darkshot.dng (raspiraw, Software tag = "raspi_dng") darkshot+raw.dng (rpi2dng, Software tag = "raspi2dng") I plotted codes [0, 31] from the entire [0, 65535] range for G1: DNG_Comparison.png Observations: The pixel content of the two is similar, but different. T...
by blindbloom
Mon Dec 14, 2015 12:59 am
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I guess the bottom line is that the originally posted problem has now been solved (despite the involvement of imperfect individuals like myself). I'm glad for that.
by blindbloom
Sat Dec 12, 2015 1:21 am
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Ok. I figured this all out. The (mostly undocumented) raw data is appended to the end of the JPEG file, as described elsewhere. The pixels are 10-bits each and four sequential pixels are encoded in five sequential bytes. This is the correct format: Decoding.png When decoded this proper way, the "dar...
by blindbloom
Fri Dec 11, 2015 10:48 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I don't think that will help. If you think about the effect of swapping b0 and b1 of each pixel, you get this mapping: 00 -> 00 (no change) 01 -> 10 10 -> 01 11 -> 11 (no change) If you look at any of the graphs (jbeale's) there are eight columns that contain anything significant. Let's number them ...
by blindbloom
Fri Dec 11, 2015 9:03 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Here is the same plot of jbeale's image. Very different from the other. The stepped look is not present. Since this is a different camera manufacturer (but using the same sensor), I guess we still cannot be sure what the cause of the stepping is.
RPI-raw1.png
Corrected G1 and R graphs.
RPI-raw1.png (11.94 KiB) Viewed 3478 times
by blindbloom
Fri Dec 11, 2015 7:53 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I agree that noise is an issue and a problem. But Schwabenchris was concerned about the non-Poisson shape. There is something else going on here besides noise that is causing the "stepped" look. So I was wondering if this is a one-off, or a characteristic of all RPi cameras. If anyone can repeat the...
by blindbloom
Fri Dec 11, 2015 5:46 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I took a close look at the Jpeg+Raw file and plotted a histogram of the lowest 32 codes (out of 1024) for each of the Bayer filters (G1, B, R, G2). From these histograms, I conclude that over this range of codes: Bits 0 and 1 for red and blue are approximately uniformly distributed random numbers (w...
by blindbloom
Thu Dec 10, 2015 3:56 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Thanks for sharing this interesting histogram. The RPi camera captures 10-bits per sensor element. My interpretation of the stepped appearance (each step is four lines wide in the histogram) is that the two LSBs of each sample is uniform noise. Only the eight MSBs contain valid image data. For examp...
by blindbloom
Mon Jun 22, 2015 10:34 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

This is all great information! In most (all?) DSLR raw formats, the Bayer order is encoded as four numbers, for example 0, 1, 1, 2 means RGGB. For RPi RAW, it is an enumerated type! This enumeration also works for the "old firmware" images (I know, who cares?). In an attempt to document the known pa...
by blindbloom
Fri Jun 12, 2015 10:40 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I assumed the masked sensor data was being included in the RAW file in my post of June 10, where I thought 2608 sensors per row, with 8 masked sensors on each side (8 + 2592 + 8 = 2608). But others have since said that the "padding" in the byte stream between rows was uninitialized memory (i.e. garb...
by blindbloom
Thu Jun 11, 2015 10:16 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

It is true that for most people, RAW is not useful. But for others, it is very nice to have. I was surprised and very pleased to discover that the option is available on the RPi. Based on information from 6by9, jbeale and others, I have made another pass at an example C++ snippet that makes use of t...
by blindbloom
Thu Jun 11, 2015 4:35 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I am a documentation oriented guy and would be very willing to produce a more formal document describing the RAW format. But I lack reliable information. Most of it is speculation. Based on an earlier comment, it appears as though the black-level compensation has already been applied to the values i...
by blindbloom
Thu Jun 11, 2015 3:41 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

Thanks, 6by9. That is very useful information. I was going by info in the ov5647 specification, which reads: Of the 5,132,544 pixels, 5,038,848 (2592 x1944) are active pixels and can be output. The other pixels are used for black level calibration and interpolation. The center 2592x1944 is suggested...
by blindbloom
Thu Jun 11, 2015 12:28 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I should not have said anything in my original post about the flip state. I have edited it with a strike-through. 6by9 is right about who cares about old firmware? But curiosity isn't a bad thing. Well, unless you're a cat. And I also agree that the use of metadata (like Bayer filter order) is much ...
by blindbloom
Wed Jun 10, 2015 9:54 pm
Forum: Camera board
Topic: RAW output information
Replies: 236
Views: 88973

Re: RAW output information

I have looked into the format of the RPi RAW files, trying to better understand the details. I know this topic has been kicked around on this thread for a long time, and perhaps all the bits and pieces are scattered among the various posts. Here is what I have found. The ov5647 has a sensor array of...

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