This article is heavily collaborated work between myself and ^ClefairyKid.  The images are all hers, and I thank her for the use of them and the explanations she provided.

We touched on colour count loosely in the first article of the week, here, and it has been mentioned through out since.  And a lot of people don't quite get what the term means, so this should be a thorough explanation.

What is colour count?
To most people, the amount of colours in a piece of art work would be viewed as "I used blue, green and purple, so 3 colours".  In Pixel Art that is not the case; colour count refers to the number of unique values in a piece.  Every shade of blue counts as a separate colour; if your piece is made entirely of 10 shades of blue, you used 10 colours.

Here is a visual example.
and

The first rose was created using pixel techniques as well as layer opacity changes and blend modes.  So while not using any tools that automatically anti-alias, like computerized brushes or gradients, the colour count on this piece did skyrocket. 


This is a zoomed in version of the first pixel rose.  It is hard to pick out individual colours at a glance, but it can be done and we can see that there are a lot.  To find out how many in Photoshop, you can click save for web and devices.*


The colour count is in the bottom of the save for web screen (100% dither, Selective Pallette, 255 colours).  Because this piece hit the limit of colours accepted for a .gif save format, there may have been even more colours than that.  Because of all of these factors, this first piece was placed in the Icons category, where colour count is less important.

The second rose "made with the advice of :devpixelerjeremy: , contains 30 colours, proving that even a piece with lots of different hues need not have too many colours, as the colours used for shadows and highlights can be used create the illusion of working together with other areas of the same picture, which also creates a really nice feeling of harmony throughout the whole images."  (Direct quote from ^ClefairyKid )

Here is the zoomed image:

It is easy to see the number of colours in this piece, compared to the first one.



"Although some might prefer the effects of the first one, others may prefer the effects of the second one, which is the reason we are looking into the definition of the medium in the first place."  One of the questions we posed early on was "how many colours is too many?" because dA does not enforce a colour count.  You can use entirely pixel techniques but then change a layer opacity and no longer have a "traditional" pixel piece.  There are also those that do not use layer opacity changes and still come out with a colour count over 150 unique colours. 

We started a discussion here a month or two ago, and it is an important question for the future of a media that has more options now available to it than when it first started; we have save formats that preserve pixel quality with more colour options than .gif allowed for.  We have tools like the line tool in MS Paint that does not disturb colour count but also means that not every pixel was hand laid.  The standard of a lower colour count is still important to many members of the pixeling community and was held as one of the defining attributes of pixeling in the past, but currently, it is coming under scrutiny from newer members or those that simply enjoy experimenting within the media, that keep to traditional techniques but enjoy the wider range of colours now available.  So we circle back to the importance of clarity and understanding as well as acceptance.

_{*For those without Photoshop that want to check colour count, Iaza.com is free to use; all you need to do is upload an image and it will give you a colour count read out.}