Re: 8 verses 16 bit

[David Chien <chiendh@xxxxxxx>]

Basically, the more bits you have, the more colors you can reproduce or
use within your files.

Because bits refer to the binary bits used in a computer, you can
calculate the number of colors you have total under each system.

eg. 8 bits = 2^8 (2 raised to the power of 8) = 256 shades per color
R, G, B (red, green, blue, the three colors used in emmissive display
systems to create all other colors).

256*256*256 (rgb) = 16 million colors

16 bits = 2^16 = 65536 shades per R, G, B color

65536^3 (rgb) = 281 trillion colors

----

Human color vision studies easily show that the human eye can easily
see more colors than what the 8-bit color range can support.

In fact, simply looking at just one color, R, G, or B, alone will
make it easier for most people to understand why.

If you only have a 8 bit color system, Red, let's say, can only
have 256 shades total!

As you well know perhaps from working with a bit 64 color Crayola box,
there are far more shades of red than 256.

As a result, using a 8-bit color system immediately prevents you from
recording subtle color shading in certain types of photography - eg.
flowers, skin tones, etc.

----

Now, what happens when you manipulate these colors in a photo editing
program?  If you increase the contrast/brightness/gamma/etc. of the image
what you will notice is 'banding', or sudden jumps in what was otherwise
smoothly shaded areas of color, casued by the lack of intermidiate colors
that are required for accurate color adjustments.

You can understand it this way, if you only have two shades of red,
very bright red, and very dark red, how do you display a blush red?

You can't because there isn't enough colors in between - this is what
an 8-bit color system does to your images before and after editing.

=----

So how many more colors are enough?

One simply looks to various sources - film scanners, 3D raytraycing used
in movies, human vision studies, 35mm film, etc. and you'll see a varying
range being used, all greater than 8-bits because it has long been known
to be inadaquate.

16-64 bits are all in use, and I myself would prefer at least a 32-bit
color system to stay in sync with higher-bit applications in other
industries (esp. 3D animation for movies and commercials), to be
able to display that 32-bit image w/o any dithering or color conversion
at all on most 32-bit capable graphics cards (just about every video
card made today can be set to run in 32-bit mode =- we're not talking
about cheapies cards here, either.  At least a GeForce!)

Also, this would stay in sync with the future demands of HDTV and DV
editing and compositing, etc.

16-bits would just barely be 'adaquate', as we still can guess there are
more than 65K reds, blues, or green shades in this world, and it's
already not being used for higher end rendering in the 3D graphics world,
having been surpassed by 24 & 32 bit pipelines.

-----

A quick look at the histogram in any paint program (preferably Paint Shop
Pro because Photoshop 1-6, and probably 7, still STUPIDLY does not allow
you to have it up all the time to let you color correct in real-time by
eyeballing it) will let you see the harsh effects of an 8-bit color
system.

Simply take any image, then push the gamma/brightness, contrast, hue,
saturation, up a lot.  You'll notice that the histogram oftenbecomes
broken, with a smooth curve turned into a curve that has a lot of thin
slices taken out of it.

This is what happens when the system does not have enough intermediate
colors to dither to.

While this still occurs in a 16+bit system, the visual artifacts such as
banding are far, far less noticable, if at all.  More bits simply lets you
calculate things far more accurately.

----

Also, 16-32bit systems would let everyone work with their raw scans and
digicam images without further dithering and translation into a lower
8-bit image, which also introduces inaccuracies and throws away good data.

Film scanners often work in 10-16bit modes, and high-end digicams from
such makers as BetterLight.com and PhaseOne.com (yep, $10,000+ 5000x5000
to 10,000x10,000 pixel digital cameras!) can output raw 16+bit images.

-----

Aside from the commerical uses, the medical industry would also benefit
from photo editors that use 16-64bit image modes.

After all, you definitely don't want a spot to be misdiagnosed as cancer,
let's say, would you?

Many scientific and other industries would benefit greatly from a
higher-bit photo editor.


-----------------

   Anyways, all this talk may or may not be useful for the layman who
rarely color calibrates, color manages, or cares for the 'most' accurate
colors his PC system can display today.  He may simply ignore all of our
talk, sit back and enjoy the 8-bit age for the rest of his life.

   For the rest of us neurotic types, I say it's rather 'lame' excuse that
after 6+ generations of Photoshop, not one thing has been done to migrate
the entire system to a flexible non-hardcoded-bit based system!

 Any good programmer can easily create filters and other routines that
will accept
1) older plugins (which would simply get fed translated higher-bit to
8-bit data, andresulting output would be degraded as if you were working
in an 8-bit mode) and
2) newer plugins that would work in any bit mode up
to a 'reasonable' value, let's say 256 bits.

No work would have to be done at all to let the user continue using older
filters with the latest high-bit enabled photo editing program because
those filters would simply see the old 8-bit interface.

The only thing that would have to be done is to write new filters that
work in multi-bit mode, which is not a bad thing since that means filter
makers would release new upgrade versions everyone buys, just like they
spend money today to buy new versions of all software.

-----

Okay, enough ranting with one close: if Adobe IS hiring lame sub-standard
programmers that arent' as good as their better ones, then what the hell
are the managers there doing? why are shareholders supporting this? and
why not fire them now? No wonder they haven't the 'manpower' to get apps
migrated to full 16+bit modes by now - paying idiot programmers to sit
around cluelessly.

It's not like you walk into a supermarket and pickup just any apple to buy
now do you?  No, you take only the best apples, and the rotten ones get
tossed back into the pile to rot.

Gee, or maybe they should raise the price on Photoshop again to hire some
more ace programmers that can do it right, on-time, and fast.

d =)

-
Turn off HTML mail features. Keep quoted material short. Use accurate
subject lines. http://www.leben.com/lists for list instructions.