Digital Darkroom; Photoshop Basic Adjustments to Light

The Digital Darkroom is a series of posts aimed at beginners and those interested in Digital Photography and Editing. In previous weeks we have looked at basic adjustments, curves, editing colour with the HSL/Color panels, black and white toning, split toning, local adjustments, sharpening, noise reduction and Lens Correction and Camera Calibration in Lightroom and Adobe Camera Raw. Moving into Photoshop we have looked at the programs layout and this week basic adjustments to light using Levels, Curves, Exposure and Brightness and Contrast adjustment layers.
If you wish to check out previous posts in the series you can do here.

I think what I took away from working in the darkroom as I transitioned to the digital darkroom was my process of editing; first balancing light, then adjusting contrast and finally selective adjustments. In Photoshop there are many ways you can approach basic adjustments to the tone of the image.

Firstly, I like to work non-destructively using smart objects and adjustment layers. The reason for this is I am able to go back and make adjustments after the image has been saved. Using layers is useful when editing because you can turn on and off layers to see how you adjustment has affected the image.
People say to me that layers are too advanced for them. There is nothing different about using layers to using image adjustments, in both you make changes to an image except with layers a stack of adjustments in the layer pallet. In the beginning level you don’t have to do anything more.

To add an adjustment layer you can either use the menu or choose layer and then adjustment layer or you can use the button at the bottom of layer pallet.

There are four main adjustments for adjusting light; Levels, Curves, Brightness and Contrast and Exposure. They all work differently but can create a similar effect.

Levels

With levels adjustment you can move siders quite easily to get the affect you want. The levels adjustment shows the histogram of the image (a graph showing the tonal range of the image) with three markers for shadows on the left, midtones in the middle and highlights on the right. In moving these sliders you are pulling and pushing the tones setting where the whitest tones, darkest tones start and where the grey tones sit in the middle. There are also three eye droppers, one for whites, midtones and blacks. By clicking on the eyedropper you can select a tone to be represented as the darkest, highest on the middlish of the image; this is then shown in the adjustment.

You can also reduce the clipping of whites and blacks (clipping is when tones are those that are completely black and white and hold no more information, although an image does need tones that are absolute black and white to create contrast, large areas though are not pleasing to the eye) by adjusting the output levels at the bottom of the adjustment panel. Sliding the black point will reduce clipping on the black pixels and the white same. It works by reducing the number of tones that are seen. For example instead of tone 0 being the darkest, tone 10 will be the darkest viable tone and instead of tone 255 being the brightest tone 254 will be. This does result in reduced image quality because tones have been thrown out of the window and the tonal range of the image has shrunk.

Levels adjustment is good for setting the white and black point of an image and making a general adjustment to the brightness with the midtones.

Curves

Curves work in exactly the same way as they do in Lightroom and Camera Raw. Curves can adjust colour and light. Curves work by manipulating the curve line to brighten tones (dragging the curve up) or darkening them (dragging the curve down). After your adjustment an anchor is placed on the curve meaning you can make multiple tonal adjustments.

As with levels you have three eyedroppers that allow you to set the white midtone and black points on and image. There is also a targeted adjustment tool then lets you mouse over your image click, drag up to brighten the selected tones and down to darken them. Once you have finished with a targeted adjustment an anchor is placed on the curve.

For me curves is a more versatile adjustment layer than levels which lets you control three areas where as with curves you can adjust several tones throughout the image.

Brightness and contrast

Brightness and contrast does what it says, it adjusts the brightness can the contrast. These are global adjustments, as you increase the brightness all tones are brightened at the same rate and as you adjust the contrast, pixels brighter than the middle tones get brighter and tones darker than the middle get darker creating contrast. Because the adjustment is global it can lead to tones being clipped (becoming the whitest pixel or the darkest pixel)

Since the contrast that is applied is unified, I seldom use it unless I need to make a tweak at the end of processing the same goes with brightness. It is a good tool if you are looking for a uniform adjustment.

Exposure

Exposure like brightness and contrast does what it says; you can adjust the exposure of an image. Exposure has three siders;

Exposure brightens and darkens the image, with a preference of adjusting the highlights more.
Offset allows you to control how much the shadows are affected by the exposure slider, by tweaking this you can see that the shadows can easily become washed out.
Gamma Correction is like a midtone controller brightening or darkening the midtones.

There are also three eyedroppers; whites, midtones and blacks, which let you, set the points of these tones that are then reflected in the adjustment.

This adjustment layer for me is rarely touched as I feel I can do more get better results with curves. The exposure adjustment does work well when editing a 32bit HDR image processed in Photoshop and can help balance the image.

Which to use?

In Photoshop which tools you use is really up to you and the ones you are most comfortable using. Personally I don’t use brightness and contrast or exposure very often because the adjustments are far too global. Exposure is good when a picture is underexposed but I feel you can get better results with curves. Brightness and contrast is an adjustment that I would use for final tweaks but rarely at the beginning of processing.

My preference is to use levels and curves. I use levels for setting black and white points in the image and the general brightness and then curves to target specific tones of an image.

In the image above I used levels to set my black and white point and midtones like the exposure slider in Lightroom to brighten the middle tones. I also used the output to soften the blacks reducing the clipping of black tones.
With the curves I brighten the midtones by moving the centre of the curve up but protected the highlights and shadows by dragging anchors back on these levels.
In the image above you may notice a bit of noise. Noise is present because I have really pushed the pixels, looking at the histogram it resembles a comb, it has teeth and gaps in between. Those gaps are missing tones and they are mainly in the shadows making noise more prominent. This noise is a by-product of edit especially when you edit aggressively on under exposed images.
In the image below I have applied colour adjustments as well as used noise reduction software to finish off the image.

Next week we will look at basic colour adjustments in Photoshop.

If you have any questions or comments please use the comment box below, all are welcome as this series is designed to help people learn how to use Photoshop and Lightroom.

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