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How to see raw RAW image?

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Offline ISO64

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How to see raw RAW image?
« on: 11 / April / 2008, 14:56:45 »
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As I understand it, RAW files are coming directly off the CCD that has its pixels arranged in Bayer pattern:
GBGB...
RGRG...

I used a couple of different editors capable of opening raw files, in my S3 IS case *.crw files. Never seen the pixels that would have only an appropriate RGB component displayed. As an example, a photo of a grey card should still have only GBGB,...RGRG,.. pattern, with exclusive G, R, or B values (0 to 1023 for 10-bit image), others (RB, Gb, GR) at 0. Looks like I can not find a way how to bypass or skip interpolation and/or de-mosaicing. Tried with PhotoLine, Irfanview, UFRaw,...

Am I missing something ?

« Last Edit: 11 / April / 2008, 22:31:34 by ISO64 »


Re: How to see raw raw image?
« Reply #2 on: 11 / April / 2008, 17:48:10 »
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« Last Edit: 22 / April / 2008, 17:28:53 by Barney Fife »
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Offline ISO64

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Re: How to see raw raw image?
« Reply #3 on: 11 / April / 2008, 21:42:05 »
It is a jungle out there, on the web, trying to find that open source utility Barney mentioned. Still looking for it... :(

There are some cameras that do just that: output RAW data as B&W high resolution image, mapped as a grey scale image, Sigma DP1 is one of them.

But, wait a moment, here is a brave proposal: CHDK programmers may try to implement this as an option in RAW Develop functions: Hi-Res B&W development/conversion. Take each pixel, originaly in RGB only, and convert it to 10-bit B&W image. The resulting resolution should equal one obtained with 4x more pixel sensors (double horizontal times double vertical resolution, since the pattern repeats itself in 2x2  pixels) or, for real objects, two times longer lens focal length, super-hyper long zoom. Save the result with appropriate extension and get ready for a storm. And, please do not tell me that there is a harware limitation that makes this impossible to code.

Nice cherry on top of already extraodinary CHDK cake!



« Last Edit: 11 / April / 2008, 23:18:52 by ISO64 »


Re: How to see raw RAW image?
« Reply #4 on: 11 / April / 2008, 23:41:46 »
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« Last Edit: 22 / April / 2008, 17:29:14 by Barney Fife »
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Re: How to see raw RAW image?
« Reply #5 on: 13 / April / 2008, 09:01:16 »
In Photoline if you use the "Linear" interpolation algorithm, you'll get close to what it might look like. I find it interesting to play with that at times.

The author of Photoline also mentioned (long ago) the possibility implementing a high-resolution B&W mode where the raw value of each photosite is used as a gray-value. I believe I read something somewhere on their forums a long time ago about some open-source project online somewhere doing just that. Getting the equivalent of a 20 megapixel B&W image from a 5 megapixel sensor. Though there is a problem with trying this. Any purer colors get displayed as a very fine checker-board pattern instead of smooth gray values. It was suggested that a color look-up table could be used to even out those checker-boards into smooth gray areas.

Do a hunt for that open-source high-resolution B&W images from RAW data project, I believe the author of Photoline said they had viewers to see the RAW data in their true Bayer patterns.


How can you get a 20Mpixel from a 5Mpixel sensor?
The 5Mpixels represent all the photosites, where 1/4th are red, 1/4th are blue, and 1/2th are green.
So when you convert all this data to a fully rgb pixels, you get -approx- 40bit fully colored RGB (5/4)Mpixels. (Jpeg reduce the color depth to 24bit along with "inflating" back to original resolution)

So in B/W you "give up" the color information, and just use the grayscale 0-1023 values for each pixel. Therefore you stay with 5Mpixels, unless you reduce the bit depth to extrapolate more resolution pixels.
Ain't that correct?

Re: How to see raw RAW image?
« Reply #6 on: 13 / April / 2008, 10:19:08 »
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« Last Edit: 22 / April / 2008, 17:29:39 by Barney Fife »
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Offline fudgey

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Re: How to see raw RAW image?
« Reply #7 on: 13 / April / 2008, 10:23:22 »
How can you get a 20Mpixel from a 5Mpixel sensor?
The 5Mpixels represent all the photosites, where 1/4th are red, 1/4th are blue, and 1/2th are green.
So when you convert all this data to a fully rgb pixels, you get -approx- 40bit fully colored RGB (5/4)Mpixels. (Jpeg reduce the color depth to 24bit along with "inflating" back to original resolution)

So in B/W you "give up" the color information, and just use the grayscale 0-1023 values for each pixel. Therefore you stay with 5Mpixels, unless you reduce the bit depth to extrapolate more resolution pixels.
Ain't that correct?

I'm not an expert so I may be wrong, but I think the idea is that in the sensor the physical pixels that are sensitive to each color may be located next to each other and not on top of each other. If so, there will be more resolution available for greyscale (but also geometrical problems if the layout isn't uniform, and the different colors obviously need proper weighting).


Re: How to see raw RAW image?
« Reply #8 on: 13 / April / 2008, 12:35:35 »
How can you get a 20Mpixel from a 5Mpixel sensor?
The 5Mpixels represent all the photosites, where 1/4th are red, 1/4th are blue, and 1/2th are green.
So when you convert all this data to a fully rgb pixels, you get -approx- 40bit fully colored RGB (5/4)Mpixels. (Jpeg reduce the color depth to 24bit along with "inflating" back to original resolution)

So in B/W you "give up" the color information, and just use the grayscale 0-1023 values for each pixel. Therefore you stay with 5Mpixels, unless you reduce the bit depth to extrapolate more resolution pixels.
Ain't that correct?

I'm not an expert so I may be wrong, but I think the idea is that in the sensor the physical pixels that are sensitive to each color may be located next to each other and not on top of each other. If so, there will be more resolution available for greyscale (but also geometrical problems if the layout isn't uniform, and the different colors obviously need proper weighting).


No... If the camera is 5Mpixels, then there are 5M photosites, thus 5M different light intensities can be recorded, no more!
In B/W picture you get EXACLY 5Mpixels with 10bit precise for each.

The way i see it, and i'll be happy if someone corrects me, it seems mathmatically you get a REDUCTION IN RESOLUTION in color mode, since 2x2 four different color pixels combine together to join their R, G, and B components to a fully colored pixel like we see on a screen.
That gives you quarter the resolution (in this case only 1.25Mpixels) but with 40bit depth for each of them (20bits for the green). JPEG then "inflates" back the data to 5Mpixel size in the cost of reducing the bit depth to 24bits, and still, when you zoom in to a 100% crop on an image, you can see that in it's fully true resolution, as you see it on the screen, it looks a bit soft, and i believe it is related to the 2x2 pixel joining issue!

Re: How to see raw RAW image?
« Reply #9 on: 13 / April / 2008, 12:42:40 »
In fact, that means that EVERY DIGITAL camera in it's full color resolution is interpolated, the thus, saying that having an 4000x3000pixels out of 12Mpixel sensor is simply a fake, and reminds me of the first years of digital cameras, where companies stated the interpolated resolution of the camera instead of it's true sensor resolution. :)

You can simply approve what i'm saying by shooting a RAW image and look at the softness of pixels at 100% crop at 1:1 zoom.

 

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