Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, claudej1@a... wrote:
> In a message dated 12/17/2004 8:49:22 AM Pacific Standard Time, 
> DigitalBlackandWhiteThePrint@yahoogroups.com writes:
> 
> Misinformation is worse than ignorance.

Agreed...

There is some minor misinformation, and some major misinformation in your replies, so I'll address that, but not in all caps. Despite your disclaimer, it is shouting. And, from a human perceptual viewpoint, it slows down the information flow, considerably.


> (There are about 50% more green sensors than those filtered for red
> > 
> > and blue, once again to provide more luma information.)
> 
> THERE ARE TWICE AS MANY GREEN SENSOR ON A NON-FOVEON BAYER ARRAY SENSOR, NOT 
> HALF AS MANY.

He didn't say "half as many". That's what "more" means. Now, it would have been better if he had gotten the number right, and said "100% more" or "twice as many", or if he had simply left the number off and said "more". But he never said "half", which is not more.

> DON'T MAKE THIS KIND OF ERROR ON MY PAYCHECK OR TAX RETURN. THE 
> FOVEON HAS ALWAYS HAD THE SAME NUMBER OF SENSORS FOR ALL 3 COLORS.

Yes, but not the same resolution, because of diffusion. This most strongly affects the red layer, hence the need for red sharpening in the raw processing algorithms. 
  
> > And it is impossible for there to be such a thing as an "interpolated'
> > RAW file: either it is RAW info, or it is interpolated info, but it
> > cannot be both, by definition.

Have a look at an SD9 or SD10 raw file in "medium" resolution. The horizontal and vertical pixel counts aren't even multiples of the sensor's pixel pitch (like they are in "low" resolution) so the Foveon VPS (pixel binning) isn't what produces the medium resolution. It's (gasp) interpolated.

> RAW is what the CCD photo sensors put
> > out: period. (I understand the confusion, the tyranny of words, that
> > can arise, since the Foveon only puts out a "raw" file, but to keep
> > the terminology correct, once that file is interpolated, it is no
> > longer "raw" in the sense normally used when speaking of digital
> > camera RAW files.
> 
> 
> ARE YOU TALKING ABOUT COLOR INTERPOLATION? FOVEON DOES NOT COLOR INTERPOLATE, 
> EVER. TYRANNY INDEED.

Actually, it does interpolate, and quite elaboratly. There have been some excellent technical papers by scientists at Foveon and HanVision (a maker of industrial cameras using Foveon sensors) explaining how the output of the Foveon sensor isn't colormetric, and conventional processing (such as the linear 3x3 matrix transforms) used with Bayer filter or sequential color filter cameras produces color errors. Therefore color interpolation (such as the 3-space to 3-space interpolation used in ICC profiles) is applied to increase color accuracy.

The SPP software also appears to lean quite heavily on other color interpolation techniques such as memory color recognition.

> > Yes, the Foveon is great, particularly for color. Excellent stuff. But
> > there is a trade-off on sheer resolution vs the lack of need for
> > anti-aliasing. Bottom line, for color, is how you like the result.
> > It's the photo, stupid!  :-)
> 
> 
> THIS IS THE ONLY TRUE STATEMENT YOU HAVE MADE SO FAR. JUST LUCKY I GUESS.

You're really not doing all that well, yourself. 
> > 
> > But for B&W, if using RAW files, then there is no anti-aliasing, and
> > no matter how you slice the pie, 3.5 megs is less information than 6.1. 
> 
> 
> FOVEON RAW FILES HAVE HISTORICALLY BEEN 12 MEGAPIXELS, 16 MEGAPIXELS (ON 
> THEIR MONOCHROME SENSOR, NEVER PRODUCED) OR 10.5 MEGAPIXELS ON THEIR CURRENT X3 
> CHIPS. THEY HAVE NEVER BEEN 3.5 IN RAW. THEY ARE 4.5 ON THEIR SMALLEST CHIP, NOT 
> YET IN PRODUCTION CAMERAS, BUT FORTHCOMING IN POLAROID CAMERAS, IT WOULD 
> SEEM.

Pixels (outside the world of Foveon marketing literature) are spatial. The X3 sensor has 3.4 of them. It doesn't matter if you sample 1 color, 3 colors, or 31 colors at each pixel, it's still a pixel. I enjoy working with Foveon cameras, but their attempted redefinition of the term "pixel" is, as far as I'm concerned, an excellent example of your old salesman's credo "BS spoken with conviction sounds better than the truth."

p.s. it's actually a political observation, typically referred to as the doctrine of "the big lie", not a salesperson's credo.

"Nothing overshadows truth so much as authority."
                      ---Leon Battista Alberti

"Tell a lie loud enough and long enough and people will believe it."
            --- frequently attributed to Adolph Hitler, sometimes to Joseph Goebbels, probably spuriously in both cases.