Photo Tip: Touch of Colour Technique

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I have been experimenting over the last few weeks with converting photos (see more) to black and white but leaving one small element of colour in them such as the couple of photos with this article. I use an older version of Photoshop Elements (the junior version of Photoshop!) but the general technique should work with most photo editting programs.

The general method is to add a second layer of the same photo over the original and then convert that to black and white (by desaturating all the colour or similar). Small elements of the black and white photo are removed and the resultant colour unearthed from the lower layer shows through revealing the touch of colour.

Here's the step by step guide using Photoshop Elements.

1. Seelct your favourite photo.

2. Click on Layer > New Adjustment Layer.

3. Select Gradient Map (and pick the black and white from the drop down). Note that the foreground colour is now black and the background colour is now white in readiness for step four below. Alternatively, select Hue/Saturation and move the saturation slider to zero.

4. Click on the white square that shows as the adjustment layer (see diagram right with red circle and click on it for a larger view). Ensure black is the foreground colour and use brush or pencil to colour over the element that you want to be coloured. Selection commands such as lasso and magic wand can be used to reduce the risk of colouring over the lines.

5. Relax if you colour over the lines. If you wish to convert some areas back to black and white, switch the foreground/background colour so the foreground colour is white and paint away removing the colour again (hitting "X" automatically swaps the two colours around).

6. Save as a .psd if you wish to work on it further but otherwise simply sit back and enjoy your handiwork.

I'd love to view some of your efforts - please share them in the comments below.

Photo of the Week: A Touch of Colour

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I have been impressed by the striking nature of some web photos I have seen where the image is in black and white but with a touch of colour being used as a highlight. I'd love to know what you think of this style of photo.

This lighthouse has guarded the southern entrance to Sydney Harbour for over 150 years and is painted a striking red and white like that of a barber's pole. Is this a more interesting photo when the blue of the ocean and the green of the grass are desaturated and only the lighthouse remains with any colour?

Similarly does the violets of the water hyacinths in a Kenyan national park become more striking when the surrounded lily pads are turned monochromatic?
For some photos, it is difficult to decide which element to colour. During a recent Sydney festival, this fine musician plays the accordian and saxophone equally adepted, yet does the rich crimson of the accordion make for a more striking photograph?

Or does the silky gold of the saxophone win the day? Or would a full colour photo be preferred?

Please share your opinions on this style of photography. A following article describes the touch of colour technique using Photoshop Elements but the general method should work similarly for any photo editting program.

Photo Tip: Painless Panoramas with Autostitch

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Connecting photos together has always been a challenge. For the last few years I've been using an amazing piece of free software called Autostitch. Developed by a pair of Canadian university students for their thesis, the software takes a collection of photos, analyses their content and automatically joins them both vertically and horizontally into a panorama.

The program is based on the photographer taking a series of photos of a landscape from one location in any sequence you wish. It doesn't matter if the camera is set on automatic, as the program will automatically adjust for changes to light, scale, orientation, exposure and aperture settings of the different photos. Photos without any overlap are conveniently ignored. Autostitch even works with photos scanned from film.

In my example, I took a series of fifteen photos of Purling Brook Falls in south-east Queensland (Australia). Individually, they look like a random collection of shots, though all overlap each other. When fed into Autostitch, the jpeg image at the top of the post results. Cropping this photo gives a final excellent panorama without the usual hassles of connecting photos or correcting any anomalies such as the strange banding which invariably occur with other software.

The user interface is terrible and the instructions scant. Easiest is to group all the relevant photos in a single folder and use all the photos in that folder as input (use File > Open). The output will be a photo called pano.jpg into that same folder. This needs renaming to avoid it being over-written by further runs of Autostitch.

Additionally, I recommend altering a few options (under Edit > Options tab) as follows:
  - set the width of the panorama (or scale) noting that making this much larger considerably slows the program;
  - consider enabling gain compensation which modifies the darkness or lightness of the various photos to make them consistent;
  - set the JPEG option in the bottom right to 90 or 95 to improve the quality of the final panorama (less compression).

With most of the options being indecipherable (terms like theta max and psi orientation abound) to all but the most astute mathematician, I'd suggest leaving them alone. Indeed, Autostitch does a great job without altering any options at all. If mathematics and image gymnastics is your thing, a detailed conference paper on the science behind the technology is available. A forum entry details the best description of all the options (scroll down a little).

Finally, note that the program is only available as a trial so it will eventually expire (after a year or more) and will need to be downloaded again. The technology has been incorporated into a number of commercial photo editting programs as shown on the Autostitch website.

Download a copy of Autostitch and start building your own painless panoramas.