November 2011 - Digital Group - High Key Images

Meeting Notes March 2009 to 2018.
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spb
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Joined: Tue Mar 25, 2008 7:04 pm

November 2011 - Digital Group - High Key Images

Post by spb » Fri Nov 04, 2011 5:11 pm

A full house – and thanks for bringing your photos.

IPHONE 4S

I took delivery of an iPhone 4s this week and tried out the camera before anything else. An A3 print was passed around and everyone agreed that it was remarkable. Pin sharp corner to corner and certainly capable of competitive use. The spec is impressive too (some details are still speculative);

- 8 Mpx backside-illumination sensor for good low light performance
- f2.4 five element lens, reportedly constant aperture
- shutter range reportedly 1/15 to 1/2000th sec
- ISO range reportedly 64 to 1000
- LED flash
- digital zoom
- autofocus or tap to focus manually. Tap and hold to lock focus and exposure
- macro mode
- geo-tagging using in-built GPS
- face recognition (if you really must)
- built-in HDR mode, merging multiple exposures
- 30 fps HD video with image stabilisation using in-built gyroscope
- front facing VGA camera for video calls and self-portraits

In addition to this impressive spec (for a pocketable phone) there are the innumerable Apps to add further functionality such as visual effects, greater control over exposure, true HDR, panoramas etc. More on these at a later date.

I can see this camera replacing my compacts and it will certainly be the best camera in my pocket at all times.

HIGH KEY IMAGES

High Key is an image with a predominance of light tones and usually a lot of white. It may be colour or monochrome.

High key images can be achieved by the lighting and exposure at the taking stage and/or by post-processing in the computer. I will be covering the latter, although the choice of image has a major effect on the success of the treatment.

The most useful weapons in Photoshop/Elements to achieve this effect are Curves and the Dodge tool. By initially pushing the centre of the diagonal line in Curves upwards, almost to the top, the image will be dramatically lightened without necessarily losing all darker tones. At this initial stage it’s often possible to assess whether the image is going to be suitable for a high key treatment. The second step is to use the Dodge tool to selectively lighten those areas that require it. By using a low Exposure value in the Dodge toolbar and a soft-edged brush, the effect can be built up gradually. If a monochrome effect is required, the colour image can be converted at any stage. A further refinement is to use an often-ignored feature of Levels; below the histogram and it’s sliders there are two Output sliders. These can be used to lighten blacks or darken whites. The latter might be appropriate to prevent glare from a high key projected image by reducing the pure white.

Although recent versions of Photoshop Elements do have a Curves tool, it’s not very flexible and I would highly recommend a free Curves plug-in called SmartCurve

Non destructive editing is the way forward (see April and May 2011 notes) and Photoshop CS users can utilise Curves Adjustment Layers and also Black and White Adjustment Layers which can be tweaked repeatedly to achieve the desired effect. All versions of Photoshop and Elements can utilise the non-destructive method of Dodging onto a 50% grey layer (see notes). For High Key purposes this should be set to Hard Light blending mode to enable the dodging to achieve a full white.

When building up a stack of layers to achieve the required effect it can often be useful to produce a single composite layer that incorporates all visible layers. This can be achieved by selecting Alt+Merge Visible. This is called a Stamp Visible layer. NB Older versions of Photoshop/Elements may overwrite the current layer unless a new empty layer is created first and also may require the keystroke Ctrl+Alt+Merge Visible. Experiment with your own version.

MISCELLANEOUS PROBLEMS

1. A convenient way to produce a border around an image is to extend the Canvas. Sometimes this unexpectedly produces a transparent border. That occurs when the image has no true Background Layer – perhaps it’s been renamed. The cure is to convert a layer to a Background with Layer>New>Background from Layer.

2. Having created a border by extending the Canvas, you may find that Adjustments Layers are affecting the border or image layers are visible on top of the border. To cure this, undo the border and apply the crop tool around the outside edge of the image. This will crop away anything that extends beyond the visible edge of the image. Finally re-apply the border.

3. How can you change the colour of certain areas of an image eg to change the colour of an item of clothing? Here are a couple of suggestions; Method 1 - Set the required Foreground Colour either with the Colour Picker or colour swatches. Choose the Brush tool with a suitable size and softness and set it’s blending mode to Hue. Brush onto the required areas. Method 2 – Select Hue/Saturation and choose any channel other than Master in the dialogue box. Click on the required part of the image and adjust the Hue and Saturation sliders as necessary. In both methods, the best results are achieved by selecting around the area to be re-coloured first.

NEXT MEETING

Thursday 1st December 2011. *NB in the Pottery Room not our usual venue*

Cheers, Steve.

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