pixel count doubts

pixel count doubts

[Veda N]

Hi,
I am trying to write a camera sensor driver.

The sensor documents says that -
For the resolution VGA, The pixel count is 640x480x3.

I did not understand what is meant by x3 in pixel count.

Usually it is 60x480. The number of bytes per pixel is 2.

Does this mean that instead of 2 bytes per pixel. it is 3 bytes?


How should i account this pixel count in my driver.
How much should be  bytesperline and sizeimage
How should i account this in my application as well.

Regards,
vedan

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Re: pixel count doubts

[Richard Atterer]

On Fri, May 16, 2008 at 07:26:27PM +0530, Veda N wrote:
> Hi,
> I am trying to write a camera sensor driver.
> 
> The sensor documents says that -
> For the resolution VGA, The pixel count is 640x480x3.
> 
> I did not understand what is meant by x3 in pixel count.
> 
> Usually it is 60x480. The number of bytes per pixel is 2.
> 
> Does this mean that instead of 2 bytes per pixel. it is 3 bytes?

There isn't really enough information to tell, but probably yes.

Note that it is often the case that a claimed sensor resolution of, say, 
640x480 means that the _Bayer pattern_ resolution is 640x480 - in other 
words, there are that many pixels, but each pixel is only for one of the 
colours red, green or blue, and further interpolation is necessary to get a 
640x480 RGB picture.

So the "640x480x3" /could/ mean "3 subpixels for each image pixel", but I 
strongly doubt it; Foveon sensors are fairly rare in webcams. ;-)

> How should i account this pixel count in my driver.
> How much should be  bytesperline and sizeimage
> How should i account this in my application as well.

I think you will have to play around to see what the exact data format is. 

Cheers,

  Richard

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Re: pixel count doubts

[Roger Oberholtzer]

On Fri, 2008-05-16 at 19:26 +0530, Veda N wrote:
> Hi,
> I am trying to write a camera sensor driver.
> 
> The sensor documents says that -
> For the resolution VGA, The pixel count is 640x480x3.
> 
> I did not understand what is meant by x3 in pixel count.
> 
> Usually it is 60x480. The number of bytes per pixel is 2.
> 
> Does this mean that instead of 2 bytes per pixel. it is 3 bytes?

Just guessing, as I do not know the exact context, but I am guessing it
is RGB VGA, in which you are probably correct: a byte each for RGB.

> 
> 
> How should i account this pixel count in my driver.
> How much should be  bytesperline and sizeimage
> How should i account this in my application as well.

First decide if your images are RGB. Maybe they are 8-bit? Or maybe
there is an alpha channel? It is up to your application. All are
possible and valid. That is what makes all this so much fun.

> 
> Regards,
> vedan
> 
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