- Capturing the image
- Camera settings
- Care and maintenance
- Custom functions
- Digital camera features
- Digital image file
- Digital image size and preview
- EOS MOVIE
- Exposure settings
- Flash basics
- Speedlite compatibility
- Speedlite range
- Speedlite zoom
- Flash on camera
- Dark backgrounds with flash
- Fill in flash
- Flash exposure lock and compensation
- Wireless flash
- Macroflash photography
- Bounce flash
- Flash synchronisation
- Stroboscopic flash
- Studio-style flash lighting with Speedlites
- Integrated Speedlite Transmitter
- Remote Release
- Focus points
- Image download
- Image compression
- Image information
- Image verification
- Introduction to digital photography
- Focal length
- All about apertures
- Lens speed
- Focusing and depth of field
- Black or white lenses
- Coloured rings
- Lens mount
- EF-S and field of view
- L-series lenses
- Fluorite, aspherical and UD lenses
- Prime and zoom lenses
- Image stabilisation
- Tilt and shift lenses
- Extension tubes
- Macro lenses
- Close-up lenses
- DO elements
- Fisheye lenses
- SubWavelength structure Coating
- Media cards
- Panoramic images
- Remote photography
- Scanning & copying
- Storage and archiving
- The digital darkroom
- White balance
Printers: RGB and CMYK
The sensor in your digital camera is made up of millions of tiny picture elements (pixels). Each one of these pixels is sensitive to light – but not to colour. To capture the colour data of a subject, each pixel is covered by a red, green or blue filter (below, top). This means that pixels covered by a red filter are now only sensitive to red light, pixels covered by a green filter are only sensitive to green light, and pixels covered by a blue filter are only sensitive to blue light. By grouping the different filters together in cluster, and by clever processing of the pixel data inside the camera, a full colour image is created.
Computer screens also use red, green and blue (RGB) data. In fact, any imaging system using transmitted light (such as a digital projector or a television screen) uses the RGB system. With RGB, when no light is transmitted, you have black, while mixing all three colours gives white. In between these extremes, using different strengths of one, two or three of the colours gives a wide range of colour hues (below, middle).
The problem is that this system does not work when you want to transfer your image to paper. Paper does not transmit light; it reflects it. If you mix red, green and blue inks together, you get a muddy brown colour, not white. And if no inks are used, white paper remains white, not black. So, for printing onto paper, the CMYK printing process is used.
CMY stands for cyan, magenta, yellow. Mix two of these together and you can make red, green or blue. Mix all three and you get black (below, bottom). However, because inks are not perfect, the black appears as more of a dark brown colour, so a pure black ink is used to overcome this. Black is not denoted with the letter B because it would be confused with blue, so K is used instead. The result is the CMYK system.
Although printers work with CMYK and your images are in RGB, you should not perform a CMYK conversion prior to printing your images unless you are producing a hard proof to send to a client for colour matching. The printer drivers will do the appropriate conversion from RGB to CMYK to ensure the best results from your digital files.
Using a tri-colour filter over the sensor in your digital camera allows colour data to be captured. It is called a Bayer filter.
Imagine that these circles are coloured light projected onto a screen. Where all three circles overlap, you see white. Where only two circles overlap, you see cyan, magenta or yellow. RGB is known as the additive colour system.
Cyan, magenta and yellow (CMY) inks are used to print photographs. This is known as the subtractive system.
How many inks?
Canon bubble jet printers use anything from three to ten different colours of ink. In the same way that black ink is added to the CMY system to improve contrast, so inks such as photo cyan, photo magenta, red and green are used to make up for other deficiencies. It is not that the CMY system is at fault – it is just very difficult to make the perfect cyan, magenta and yellow inks.
In theory, the more ink colours, the wider the colour gamut the printer is able to reproduce. Nevertheless, printers with only six inks can still produce photo-quality prints. Professional print units use the largest number of inks (up to 12). The extra colours are only likely to be appreciated by professionals who are selling images, and require absolute colour fidelity. Although a greater number of ink colours should give better quality results, in reality, the differences are subtle – in many cases you will find it difficult to detect the difference between a six-ink print and an eight-ink print.
Bubble jet printers do not provide a protective coating. The prints are usually touch-dry as they emerge, but need a few more minutes to fully dry out. Using a high-gloss paper will give the effect of a coating and is very durable.
Inks and papers
Bubble jet and ink jet printers generally use dye-based inks. This is true of Canon’s Pixma range of bubble jet printers, with the exception of the black inks in some, which are pigment-based. Because of the way dye-based inks react with photo paper they tend to produce more vibrant colours than pigment inks; the dyes permeate the paper while the pigment inks sit on top of the paper. Because they embed within the paper, dye-based produce prints that more accurately reflect the character of the paper — for example, high gloss paper appears as a true high gloss.
Like dye-based inks, the special ‘Lucia’ pigment inks used by the Pro 9500 give 100 years lightfastness and 50 years gasfastness (the inks do not fade in the presence of ozone and other atmospheric gases) when used with Canon Photo Paper Plus Semi-gloss.
You will get the best quality prints if you use a Pixma printer with Canon paper and inks. While the third party inks may be cheaper, the Canon inks and paper are designed to work in harmony with the printer. With its combination of ink, paper and nozzle technology, Canon can claim 100 years light-fastness for prints made using products with the ChromaLife 100 badge.
Although the prints are rated at 100 years, there are certain caveats. Temperature, exposure to direct sunlight, humidity and atmospheric gases all play a part in degrading the quality of a print over a period of time. The ChromaLife standard claims 100 years light-fastness for a print stored in an archival album, 30 years for images displayed in photo frames and experiencing around 10 hours of light per day (though not direct sunlight), and 10 years for images pinned on a board or stuck to a refrigerator.
Paper and profiling
No matter how good your printer, if your system isn’t colour managed, you will not be able to produce colours that are fully accurate. If you stick to using Canon inks and papers, then your prints should be fairly accurate, providing you choose the correct paper in the print dialogue box. This is because the software supplied with the printer driver includes profiles for the various types of Canon paper – this is what you select when you choose the paper type.
However, if you use a third party paper, then you’ll need to create a new profile for it. You can do this yourself, but the hardware and software that you need to do this is expensive and is only worth investing in if you intend to produce a large number of prints, using a variety of different paper types.
Selphy printers produce images very similar to the standard 6x4 inch prints you would receive if you took a film into a traditional mini-lab. They use dye-sublimation technology (with the exception of the DS-series, which uses bubble jet technology). Some are portable and run on batteries.
The Pixma printer range is the largest – and most popular – in the Canon line-up. Pixma printers use bubble jet technology to produce near photo-quality prints. For most photographers, printing to A4 is more than adequate, but there are two semi-professional models, the Pixma iX 4000 and iX 5000, which print to A3+ paper.
Most Pixma printers use single ink tank technology for more economical printing and less wastage. Although the cartridges may seem expensive, you only need to replace the individual cartridge that has run out, rather than an entire multi-ink cartridge (where some ink colours may still be available).
The Pro range of Canon photo printers uses the same bubble jet technology found in the Pixma range, but with different inks. The Pro 9000 uses eight dye-based inks, whereas the newer Pro 9500 uses ten pigment-based ‘Lucia’ inks. These printers are both A3+ printers – ideal for producing large prints suitable for selling or exhibiting.
Designed for high quality black-and-white printing, the Pro 9500 has two additional inks – grey and matt black. The extra inks mean that different tones can be more clearly distinguished. Both the Pro 9000 and Pro 9500 feature red and green inks, which increases their colour gamut.