Rockbox.org home
release
dev builds
extras
themes manual
wiki
device status forums
mailing lists
IRC bugs
patches
dev guide



Rockbox mail archive

Subject: Re: What Is Dithering?

Re: What Is Dithering?

From: Bluechip <csbluechip_at_gmail.com>
Date: Sat, 18 Nov 2006 00:31:46 +0000

What a damn good utterly OT question.
You'd think so, wouldn't you!
However, in nature, even the smallest component of an object has the
ability to absorb-versus-reflect any combination of light
frequencies. So the smallest component might reflect
all-red-frequencies and some of every other frequency - thus creating pink.
Perhaps if you went as far as individual molecules you might find
coloured dots, but you'll need a chemistry major to help you there.

BC

At 23:43 17/11/2006, you wrote:
>Off Topic, but if you magnify an actual pink rose pedal enough, you will see
>red dots and white dots.
>Glenn
>----- Original Message -----
>From: "Pieter Bos" <bos.pieter_at_gmail.com>
>To: <rockbox_at_cool.haxx.se>
>Sent: Friday, November 17, 2006 5:43 AM
>Subject: Re: What Is Dithering?
>
>
>
>"Christopher Woods" <christof_at_infinitus.co.uk> wrote in message
>news:007801c709fa$c51ffb70$4001a8c0_at_20hz...
> > I guess a comparable analogy (best I can think of right now)
> > would be if you take a large image, and resize it to a smaller size - if
> > you
> > have your settings to just go with each pixel's nearest neighbour when you
> > shrink the image, you'll get uneven lines, jaggedy edges and it'll look a
> > bit poor... Whereas if you set your image program to do bicubic or
> > bilinear
> > resizing, it looks at the pixels, their relationship to the ones next to
> > them, and 'redraws' the image in a sense, blurring together areas for want
> > of a better description, to produce a more aesthetically-pleasing result -
> > lines look smoother, colours blend and gradient better...
> >
>
>This analogy is more like increasing the time-resolution (sample rate) than
>increasing the bit-depth.
>
>Perhaps a better analogy, speaking in terms of images, is exactly the same:
>dithering. If you have only a limited number of colours, you can produce
>more colours by drawing tiny dots of different colours. Our eyes will
>automatically blend the colours, so we see a colour that is not actually
>there but which is made up of a blend of the other colours. This is applied
>for example in computer screens with a limited number of colours and in
>printers - you can see the dots in every photo in every newspaper!
>
>You can try this yourself: Get two different colour pencils and draw lots of
>dots on a piece of paper, alternating between both the colours.Make some
>different areas, some with more dots with one colour, others with more dots
>with the other colour. Make sure to draw the dots close together. Now look
>at it from a distance. You will see different colours! You can try making a
>drawing with this by changing the number of dots.
>
>If you have only one pencil available, just make drawings with dots, but
>change the number of dots in the same area (eg. completely filled, half
>filled...).
>
>In audio, the concept works almost the same. Think of the bit-depth of the
>audio (16 bit...) as the number of available colours. If you want to match a
>value that is not there, you can add some rapidly changing values close to
>the value you want to match to gain a slightly better quality audio and a
>bigger dynamic range. Now, you're performing dithering!
>
>Pieter
Received on 2006-11-18


Page was last modified "Jan 10 2012" The Rockbox Crew
aaa