[sane-devel] "gamma" and "bayer" ? What are they?

david stevenson david@rondotheatre.co.uk
Thu, 12 Jun 2003 20:00:02 +0100

On Thursday 12 June 2003 6:55 pm, Theodore Kilgore wrote:
> On Thu, 12 Jun 2003, [iso-8859-1] Thomas VIAL wrote:
> > Hi,

> Again, yes. My point was that a string of bytes equal in number to the
> number of pixels in the picture will give precisely no good result, but
> that on the other hand putting the text fomat of same data, obtained by
> suitable editing of the log file, will give a picture provided one only
> puts a ppm header on the top. In other words, if you read (for example) bc
> as one byte, and not as three bytes (one for b, one for c, and one for the
> space after it, and so on through the rest of the file) you do get a file
> but it is not a picture, but if you do it the second way (stupid as that
> may look) you do get a picture.
An interesting way to process data, but if it works.......
In converting a byte to hex it is effectivly split into 2 nibbles of 4bits and 
a fixed value of 0x30 added to each. (or 0x37 if the nibble value is more 
than 9)
So using the ascii file as data should be twice the size (having ignored the 
spaces). The question then is what headers have you added to make the bitmap. 
Most headers include information on bits per pixel, pixels per line ...