April 2014 - Digital Group - Mono Conversion

[spb]

NEWS
Only some interesting camera stories this month;
- the Nikon D600 can now be sent back to Nikon for a replacement shutter if required - it's taken 18 months to officially acknowledge the problem with dust/oil spots on the sensor.
- the Sony DSC-H400 bridge camera has a 64X optical zoom! 24 to 1500mm (35mm equivalent). Just don't go there.
- after my positive experiences with a rugged Panasonic compact last year, the Canon D30 can go to 25m depth of water and can be dropped from 2m!

COLOUR TO MONO CONVERSION
Peter Jones presented his method for colour to mono conversion;

Having originally taken a raw file, Peter converted it twice - once for a general overall exposure and once darker, for the highlights (eg the sky). The two files were then combined into a single file by selecting one of the images (Select>All), copying it (Edit>Copy) and pasting it into the other image file (Edit>Paste).

A layer mask with a soft-edged black or white brush is then used to reveal the appropriate areas of the lower image in order to combine the best parts of both. A so-called 'stamp-visible' composite of these two layers is then produced at the top of the layers palette by combining the Alt key with Layer>Merge Visible (or the finger-challenging Shift+Ctrl+Alt+E).

By changing the Blending Mode of the new composite layer to Multipy, the image is multiplied by itself and becomes much more contrasty. This can be reduced as required with the layer's Opacity control, or indeed increased by multiplying another copy.

In Photoshop CS, Peter uses the Channel Mixer but in the club's Photoshop Elements 10 he chose the double hue and saturation layer method;
- make a Hue and Saturation adjustment layer and duplicate it
- turn the Saturation slider down to zero in the upper one, thus turning the image to mono
- set the Blending Mode of the lower one to Color
- adjust the colour-to-tone conversion with the Hue and Saturation sliders in the lower one as required (Peter sets this lower layer to 'Colorize' although there are different opinions about this and I prefer not to do so, because more separation of tones becomes possible in strongly coloured images).

Further localised adjustments to the tones can now be done by selecting areas of the image. Choosing a Levels Adjustment Layer then turns the selection into a Layer Mask which can be tweaked ad infinitum at any time. The Opacity control sets the overall impact of any layer upon the visible image.

A more sophisticated method of localised tonal adjustment is to add a new transparent layer at the top of the stack and fill it with grey (Edit>Fill Layer>Use:50% Gray) Set the Blending Mode to Soft Light and then paint lighter or darker shades of grey onto the layer which will lighten or darken the image in only those areas. (NB Blending Mode 'Overlay' increases the strength of the effect and 'Hard Light' increases it further but subtlety is the name of the game here. The significance of these three blending modes is that they all ignore any 50% grey areas). An alternative to the paintbrush are the Dodge and Burn tools which work equally well on the grey layer.

All of the above adjustments can be modified later, so long as the image is saved as a .PSD file. Reversibility is the key to good image editing.

Cheers, Steve

[peterjones]

Many thanks as always to Steve for a highly informative evening.

Thank you all of you for listening to my presentation.

Laurie Turner made a very valid point from the front benches: local exposure control can also be carried out by selecting part of the image with the appropriate tool and feather henceforth darkening and lightening can be achieved with the levels tool; this process can be repeated as many times on different layers as it takes to achieve your desired result and as Laurie pointed out you can at any time in the future adjust the levels tool to taste at any time by accessing the right layer.

You can of course modify a "burn and dodge" grey layer in soft light mode at any time by using white or black paint to change your local exposure to taste.

As I often maintain there are few right and wrongs in P/S assuming basic competencies; it is a means to an end and the end result i.e. your image is the most important part of the process.

Peter.