Photoshop Colour Management

Adobe Camera Raw - Editing Images

The previous pages introduced the concept of raw images, and of opening DNG raw images in Adobe Camera Raw from Adobe Bridge. This page will mostly deal with the Colour Management aspects of using the Adobe Camera Raw ('ACR') plug-in, primarily in conjunction with Photoshop CS6 & CC. The inbuilt curves work like traditional 'S' shaped curves.

Other simpler Adobe applications, such as 'Elements', may have less ACR functionality.

Much of the basic functionality is shared with Lightroom ('LR'). These days many photographers prefer to work directly in Lightroom (or other Raw developing apps.) anyway.

This article will give you a bit more detail of the common functions shared between both applications.
The key concept is that of 'Parametric Editing', or non-destructive editing, in which the parameters of the image, as opposed to the actual pixels, are edited. These parameters are written into the metadata ('tags') of the image, and are applied when the image is opened in Photoshop as a 'real' image, such as a TIFF.

You may find that images when opened (or Auto adjusted) in ACR 7 onwards, appear rather different than in older versions, although the edit controls are more intuitive.

Displaying and Working with Images in Camera Raw

Images open into the ACR 'Dialogue Box' shown here.

The main areas of the ACR box are:

View Controls, etc. at the top left; zoom, crop image, display RGB values, show settings.

Preview, toggles display with current edits On/Off.

Image display

Histogram at the top right; Displays the tonal range of the image. Has buttons to display highlight and shadow 'clipping'.

Image Adjustment Tabs and sliders, under the histogram.

Workflow Options to apply to output images; at the bottom, control colour space, size, resolution, bit-depth, output-specific sharpening, etc.

What to Check in Images?

After opening an image, take a look at it in the display. If it looks reasonable, take sample points of critical areas with the Colour Sampler Dropper (icon has a 'dropper' and a 'target'). Don't confuse this with the very similar looking adjacent White Balance Tool (has a 'dropper' but no 'target'), which may completely change your image, unless that's what you want! The sample currently under the dropper, in RGB values from 0-255, will be displayed under the histogram, while saved sample points will be displayed above the image.

Basic settings ('Aperture' tab). Start with these, as they are the most common adjustments.

White Balance: Colour Temperature:
Begin with the As Shot setting, which is the White Balance in terms of colour temperature, in K (Kelvin), as reported by the camera's analysis of the raw image, or its metering system. You will likely find that this is about right, as in the image here. If it's just a little off, adjust the slider until it appears correct. You can also view the RGB values. Sliding the slider to the left (towards the blue zone) will show a lower colour temperature number, and will compensate by making the image 'more blue'. Sliding to the right, towards the yellow, will increase the colour temperature in K, making the image 'more yellow'. The setting will now show Custom. Setting Auto will calculate the white balance from the image data (as in histogram). You can apply lighting settings such as Tungsten or Cloudy to make big changes. If your white balance is usually wrong, an adjustment can often be made in the camera's settings.

Tint: This compensates for a green or magenta tint. To add green, drag slider to left (-), or to add magenta, drag to right (+).

White Balance Dropper Tool: You can quickly adjust the White Balance by selecting an area of the image which should be a neutral grey or white with the White Balance Dropper. You may still end up fine-tuning with the sliders however.

Exposure and the Histogram

A bit further down the panel on the left we get to the 'exposure' ('tone') settings. At the top of this 'sub-menu' can be seen Auto and Default commands. When you open an image, normally ACR will examine its histogram and automatically adjust the exposure, recovery, etc. controls to give a pleasing image using 'Auto' parameters. If you then make adjustments which you don't like, you can override these by pressing Auto. Default recalls the 'standard' settings from the camera profile, with no further adjustments for that particular image's characteristics, such as compensation for over/under exposure.

At this stage we should look at the Histogram.
A histogram is a graphical representation of an image's spread of luminance levels, showing the approximate number of pixels for each luminance level. In the case of ACR, the vertical axis displays the number of pixels, and the horizontal axis the range of luminance levels from 0 at the left, representing black, and 255 at the right representing white. A histogram will show whether the image has a good spread of tones, or is very contrasty, or 'flat', or over/under-exposed.

The histogram for a 'normal', rather contrasty, but well-exposed image at left. Has only a small amount of bunching-up at the left (shadows) and at right (highlight) ends, and a fairly even spread of pixels from almost the darkest shadows to the brightest highlights. No guarantee that it's a pretty picture however!

The histogram on the left is for an image with a lot of shadow, being somewhat under-exposed. The image at right has no shadows or mid-tones, only highlights. It's actually a picture of a seagull against a white sky!

The histogram on the left has lost some shadow detail, although the highlights appear O.K. The small triangle at the top left of the histogram changes from black to white (or a colour) to show that there is clipping. Clicking this also switches staining on/off in the image display to show clipping. Having a lot of '0s' in the image means a loss of shadow detail. This could be helped by adjusting the Shadows and/or the Black slider if it is above 0.

The right histogram shows highlight clipping, as does the triangle. The image of the Traction Engine at the top shows a small amount of highlight clipping staining, mainly in the shiny 'brass' areas. This isn't too bad for this subject, being 'exposed to the right' or 'ETTR'. ETTR, in moderation, helps to increase shadow detail and to reduce sensor noise. Having a lot of areas reading '255' should be avoided, as highlight detail will be lost.  ACR can rebuild highlight (or shadow) detail to some degree, if there is some detail in one (but ideally two) channel(s). Adjusting the Whites and/or Highlights or Exposure sliders will darken the highlights, putting detail back.

The 'Tone' & 'Saturation' Controls

The sliders standard setting is now zero (0) which is now in the centre. Use these 'Tone' controls to fine-tune the images appearance. The best order is usually to work downwards, starting with the 'Exposure' control.

Exposure: The greatest effect is in the midtones. The whites are also affected, but much less than previously. You would have to move the slider a lot to cause (or reduce) clipping. Reducing 'exposure' by sliding the Exposure  slider to the left will darken the image, while sliding to the right lightens it overall. The numbers equate to camera Exposure Values ('EV') or f-stops.

Contrast: Increasing the Contrast darkens the shadows, while lightening the highlights, while changing the 'position' of the midtones.

Highlights: Adjusts the bright image areas, aka 'quarter-tones', which are just above the whitest areas. Can use to recover some detail lost through 'clipping', although the effect is quite subtle. Improvement over the old (2010) Recovery control.

Shadows: Adjust dark image areas, aka 'quarter-tones'. Can help to reduce clipping. Improvement on the old Fill Light control.

Whites: Use this to fine tune the whitepoint, and to reduce or increase clipping.

Blacks: Use this to darken or lighten the blackest shadows, and to reduce or increase clipping.

Further down are some rather exotic-sounding controls:
Clarity: Increases local contrast, giving an effect similar to Unsharp Masking. Zoom up to 100% to view the effect properly. Quite subtle.
Vibrance: Increases saturation in less-saturated colours before more saturated colours and flesh-tones.
Saturation: Increases saturation equally in all colours. Effect is quite pronounced.

The Other Image Adjustment Tabs

Tone Curve: This also includes the option of RGB channel adjustments (as in Photoshop).

Detail: Sharpening, and equally importantly, Noise Reduction.
More information on Detail editing can be found in our Lightroom Develop section.

HSL/Grayscale: Conversion to Grayscale options, and also Selective Colour Correction using Hue, Saturation and Lightness.

Split Toning: Separate  Hue & Saturation adjustment for highlights and shadows.

Lens Corrections: Applies Lens Profiles to correct aberrations. Profiles for many popular lenses are pre-installed. Some are available from photo-enthusiasts internet fora. It is possible to make your own lens profiles using a free Adobe utility, but is very time-consuming, involving shooting a test chart at different apertures and focal lengths (if using a zoom lens).

Effects: Can apply Grain as in film, or apply Post Crop Vignetting ('fading').

Camera Calibration: Selecting Raw camera profiles.. Also enables switching to/from older ACR editing versions.

Presets: Enables saving and recall of your settings.

Snapshots: Record different versions of an image, with different edits..

Raw Images - Intro       Raw Colour Management

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This page updated January 18, 2021