COMP6023 Understanding Digital Colour I & II

These videos explains how Digital Colour works. We will be looking at this over the next few classes. The first one look at SHB and Lab.

The second video looks at RGB and CMYK.

COMP6021 Class 34 Bayer Filter, Interlaced Video

the one with the electron gun

We looked at the Bayer filer used in sensors like those in cameras.

I explained how interlaced video works and we looked at some of its side effects.

COMP6021 Class 23 Lab

We looked at an images RGB, CMYK, and Lab channels using Photoshop.

Students converted images from RGB, to Lab and then subsampled the a and b components so that they were a mere 1/36th of their original sizes. The results were surprising good in most cases.


In these images 35/36ths of the colour information has been discarded. Look closely to see the impact of this.

Original PNG.

Subsampled Colour.

If you were on holidays and paying roaming fees to upload the picture you would would pay 3.00 for the full quality picture, but only 1.05 for the low quality.

COMP6021 Class 22

We looked at the Lab system and the CMYK system. The Lab system was interesting because it separates out the luminance and chrominance components of a image. We say how subsampling the chrominance components of an image can be quite successful.

We considered the use of subsampling as crude compression mechanism and looked at interpolation to replace the lost data.  in practice, interpolation is more complex that I explained.

COMP6021 Online Lesson - Digitization

We are currently considering how real world things are digitised. This video might be useful.

Digital Colour

This week in class we will be looking at how colour is represented digitally. This video explains the Hue Saturation Brightness (HSB) system.

This video outlines the Lab and CMYK systems.

COMP6021 Online class: Image Digitization

COMP6021 Class 20

the one with the thermometers

We looked at Digitisation and saw how both the number of quantization levels and the sample rate can affect the fidelity of the digital representation of the analogue values.