Thursday, December 23, 2010

Lost in Space - Danger Will Robinson, Danger!

Colour Space Explained
  It looked blue on my computer monitor, but when my print came back from the printer it was purple... what happened? It's all about colour space.
 Computer monitors transmit colour as RGB (red, green, blue) light. Although all colours of the visible spectrum can be produced by merging red, green and blue light, monitors are capable of displaying only a limited gamut of the visible spectrum.
 Monitors transmit light, inked paper absorbs or reflects specific wavelengths. Cyan, magenta and yellow pigments serve as filters, subtracting varying degrees of red, green and blue from white light to produce a selective gamut of spectral colours.
 Like monitors, printing inks also produce a colour gamut that is only a subset of the visible spectrum, however the range is not the same for both. Therefore, the same art displayed on a computer monitor may not match to that which is printed. Print processes normally use CMYK (cyan, magenta, yellow, black) inks requiring digital art to be converted from RGB to CMYK colour for print.

                                               Red, Green, Blue - Additive colours
                                        Cyan, Magenta, Yellow - Subtractive colours

 Printers may prefer your files in the CMYK (Cyan/Magenta/Yellow/Black) mode, as this is the colour mode for the printing process. If an RGB (Red/Green/Blue) file is submitted, it must be converted to CMYK for print.
                                  Color gamut
                                            Visible colour spectrum with print gamut

 It can sometimes be difficult to visualize the reason for colour shift in colour space conversion. The best way to see the differences between the CMYK and RGB colour spaces is to look at a colour gamut comparison chart. The chart above plots the visible colour spectrum as the larger area, and within this is a plot of the CMYK and RGB colours. Some areas of the RGB colour space are outside that of the CMYK space. It is these colours that are affected by a conversion from RGB to CMYK. Some digital printers have expanded to additional shades of cmyk expanding the gamut capabilities of traditional print, but for the most part expect some colours to be "out of range" to conventional printers.
 For all the "Lost in Space" fans out there...


Thursday, November 25, 2010

New Year's Resolution

Understanding Image Resolution
 Let's start the new year with a good resolution. Ever wonder why the image you downloaded from the web looks all pixelated in print, but looked great on the web?

 Here's the short answer. Whatever we give the printer will determine the quality. Here's the explanation.
Images are made up of little "cubes" of colour named pixels. If you look at the illustration I provided, there are three different pixel counts displayed. These are all the exact same image. The 300 ppi (pixels per inch) is the original image resolution. I created the other two using Photoshop by reducing the pixel count.
 For good picture quality reproduction in printing, and to avoid the "staircasing" effect we require a minimum pixel count. This can vary depending on print process. For example, photographic prints will have reasonably good detail at 200 ppi, but 300 ppi will give you the best quality. Large format inkjet printers usually require a minimum of 75 ppi, however 100 ppi will produce a nice result. These resolution requirements need to be accurate at final reproduction size.
 For example, if a total image resolution is 2000 x 1000, divide by 100 = 20"x 10" to determine an inkjet reproduction size. Divide by 200, 10"x 5" would be a photo print size.
Some images that do not have enough resolution can potentially be used. There are programs available that "build" resolution into images, however capabilities are limited. Genuine Fractals is an excellent example and one of the better options - it works with machine language to construct resolution. Programs like Photoshop will interpolate image resolution, and are very limited in usefulness in this area.
 If you have any questions, feel free to email me at

Wednesday, September 22, 2010

Forks of the Credit on the fly

 Late September still offers excellent top water opportunities. You may need to work a little harder for big fish, but there's plenty of action with small brooks. This area has special regulations - artificial lures only, single barbless hooks, catch and possession (0) zero.
Getting there
 From Yorkdale Rd., take the 401 westbound to the 410. Follow the 410 north right to the end, and stay on hwy 10 to the Forks of the Credit Road. The Forks road is a scenic drive that will take you right to what is known as the Forks of the Credit. Park just before Dominion Street on the right shoulder. Parking is free, and this spot will give you access to both branches of the Credit and the south park entrance if you want to go up there.

Forks of the Credit from the
 Dominion St. Bridge

Forks of the Credit Provincial Park
 From the Dominion St. bridge, the south park entrance is about a 10 minute walk. (there is no parking allowed anywhere on Dominion St.)
The trails heading into the park are well groomed and markers identify which path you're on. It's easy going and there are several footpaths through the bush that will get you down to the river. The river is very tight up there except for a few locations, so you'll need to adjust your casting often. Roll casts are useful and can be rewarding to the persistent fisher. The park's nice, but I prefer south of the Forks myself.

South of the Forks
 This stretch of river is my favourite. It holds some very nice size Brooks and Browns. My personal best is an 18" Brook, but there are many in the 10 - 15" range that reside in this area. There are plenty of runs, holes, rocks and logs. Today I was fishing with a #14 Tan Caddis - dry fly. I hooked several small fish (5-8") and just missed a really nice one. It's good to see all the small ones - this appears to be a very healthy river at the top end. Let's hope it stays that way. Only a few more days and the season closes until next April. I'll try to get out again tomorrow.

Small Atlantic Salmon - kind of fun watching them come up and nab a fly.