Back to FUNCAM page Click on this link to see pictures taken with this camera. Trichromy 6x4.5cm Camera.     This very special camera has an amazing trick - it will take colour photographs on black & white film! It does this by a process called colour separation. Each of the primary colours are 'split' using filters.     Let us consider the most common picture file type, the JPEG. If you open a JPEG file in your picture editing software, you should be able to access the 'channels'. Each pixel colour in the image is defined by a red component, a green component and a blue component. Channels are a way of graphically representing, in isolation, how the red, green and blue component is distributed across the image. The channel shows you how intense a colour component is at any given pixel site.     Think of the channel as a map for each of the primary colours. For each pixel site, you can look at the red channel (for example) and see what level of this colour component is present. JPEG is an 8 bit file type. This means that for each pixel the value of red can be expressed in 2 to the power 8 (2^8) values, or 256 values. 0 would mean no red, 256 would mean full red saturation. So, you only have 256 values of red to play with and that's your lot!     Red is not the only colour component of our image. If we add green to the mix we have another 256 shades. Our pixel now has a possible colour of 256x256= 65,536 different colours. And lastly we have a blue component to our pixel. Again we only have 256 shades to choose from.     But the pixel can now have a possible colour of 256x256x256= 16,777,216 colours. That's how we get 16 million colours from 256 shades! A mix of red, green and blue should result in any colour we need.     An 8 bit image can also be called a 24 bit image because it is either 8 bits per channel, or 8red+8green+8blue which is 24 total.     Isolating one of the channels, we can see that this is just a binary representation. It may be called red for example but all it shows us is one of 256 shades (from white to black) or value (from 0 to 256) of the value of red that is present at any given pixel site. The computer allocates the colour red to the shade represented on this channel. The channel is a sort of black and white positive of the scene representing the colour red.     And of course the same applies to the other channels, green and blue. The three RGB filters can clearly be seen. Notice the 'bumps' at the edge of the frame. These will leave a record on the film 1-red, 2-green & 3-blue.     To replicate the channels, all we need are three black and white images, each one filtered red, green and blue.     This camera takes three exposures simultaneously on black & white film, (you guessed it) one is filtered red, one is filtered green & the other is filtered blue. Once the three black & white negatives are scanned into the computer, they are combined into a single image. The image from the red filtered negative is pasted into the red channel and similarily for the green & blue.     Maybe not so much a camera that takes 'pictures', but rather 'channels'. Back to FUNCAM page