Re: Decimal precision in Photoshop's info palette
Re: Decimal precision in Photoshop's info palette
- Subject: Re: Decimal precision in Photoshop's info palette
- From: Graeme Gill <email@hidden>
- Date: Sat, 20 May 2006 23:09:25 +1000
Dennis W. Manasco wrote:
Since there are 256 discrete values in the range 0 to 255, and 65536
values in the range 0 to 65535, and the ratio is 1 to 256 (or 2^4), the
mapping of an 8-bit space to a 16-bit space is fairly straight forward.
Right, so you've illustrated wonderfully the problem with insisting users
enter encoded value :-) The ratio is actually 257. (255 * 257 = 65535)
Yes. It _is_ easier to get your head around when thinking about changes
in the values, and it is easier to programmatically manipulate, but it
introduces error at the _start_ of the process because 0 to 100 cannot
be mapped onto the underlying binary representation of 0 to 255 (or 0 to
65535) without rounding error.
Using encoded values puts another "geek" barrier in the way of
most users. Most don't want to know about precise underlying
encoding, whether it's 0..255, 0..65535, 0.. 32768, 15.16 fixed
point, 16 floating point, 32 floating point, 64 bit floating
point etc. etc., they'd just like to specify the level they want.
The nice thing about a real value, is that if you are aware of
the underlying representation, you can specify the value in a way
that gets the precise encoded value you want, and if you don't,
you'll get the closest value to what you asked for.
Consider this, if an application like photoshop let you enter
a value of 50%, then it could automatically apply dithering to
a fill, to achieve that level (just like it does on smooth blends).
If you are forced to choose 127 or 128, this isn't a possibility.
Of course there is no real technical barrier to displaying and
allowing entry of both representations.
Graeme Gill.
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