Tonality Adjustments/Tonal Balancing
Merriam-Webster defines tonality as “the arrangement or interrelation of the tones of a work of visual art”. Tonality adjustments or tonal balancing with regards to image development is the method to change brightness and contrast within that image. Adjustment to the tonal balance of an image will impact color, saturation and contrast. Contrast also has an impact on image detail thus the apparent sharpness of an image can appear to be adjusted (improved).
There are four main tonality adjustments in Photoshop. These adjustments are located in the exposure section of the Photoshop layers panel. Brightness/Contrast, Levels, Curves and Exposure are all good tools for making image wide tonal adjustments. The below image shows the drop down menu of the possible adjustment types within the layers panel. To navigate to the adjustment types first click on the create layer adjustment icon at the bottom of the panel. The drop down menu will appear with the available adjustments. Click one of the adjustments to create a new adjustment layer in the layers panel.
Below is the image of the new levels layer adjustment in the layers panel after the levels adjustment was selected. The adjustment layer is where the adjustment can be fine-tuned. There are multiple ways to fine-tune an adjustment, these methods will be discussed in a later post.
Two other important tonality adjustment methods in Photoshop are the Shadows/Highlights Adjustment and Dodging/Burning. These two tonality adjustments well be detailed in a later post.
The brightness/contrast tonal adjustment is a very basic adjustment. The reason being is that with only the two sliders, this adjustment lacks some of the precise control that is often required with image adjustment. With this adjustment, highlights are brightened to the same degree that it shadows are darkened. Typically highlights and shadows should be adjusted independently in order to control contrast without impacting image detail in other areas. When shadow adjustments are limited to only dark areas, highlight detail is not lost. The opposite is also true, when brightness adjustments are limited to only light areas shadow detail is not lost. Thus the brightness/contrast tonal adjustment should be used judiciously as there are more precise adjustments for tonal balance.
The adjustment functions by moving the sliders to the right to increase brightness and contrast and to the left to decrease brightness and contrast.
The levels tonal adjustment is a more precise instrument than the brightness/contrast adjustment. The levels adjustment can be used to control the overall tonal balance of an image as well as the individual color channels. This adjustment has three sliders, shadows, mid-tones, highlights, which can be used to independently adjust those specific areas. The shadows slider (left side) sets the images black point, the darkest point in the image. The highlight slider (right side) sets the images white point, the brightest point in the image. The mid-tones slider (middle) adjusts the image contrast without impacting the the darkest shadows or brightest highlights in the image.
Since the shadows slider is the darkest point in the image moving the slider to the right “resets” the darkest point. This will darken the image and increase contrast but detail will be lost in those darkest areas. The highlights slider has the opposite effect, left movement brightens the image but detail is lost in the brightest areas.
Resetting the black and white points is called clipping the shadows and highlights. To identify the exact areas that are clipped hold down the option key while the sliders are moved this is called threshold display mode. Release the option key to exit threshold display mode.
Slight movement of these two sliders as well as the mid-tones sliders can have an impact on color, saturation and contrast. Again as image contrast is impacted the apparent sharpness can to be impacted. These slight adjustments can have a dramatic impact on the image.
The curves tonal adjustment is more precise than the levels adjustment. Just like the level adjustment, curves adjustment can be used to control the overall tonal balance of an image as well as the individual color channels. As with the levels adjustment the curves adjustment has a shadows slider (left side) which sets the images black point, the darkest point in the image. Also it has a highlight slider (right side) which sets the images white point, the brightest point in the image. The advantage of curves is that specific areas of the image can be targeted for adjustment. To target a specific area, a point is added to the tonal curve. The curve is then moved to adjust the tonal area; lighten or darkened which impacts that tonal area’s contrast.
One common method to increase contrast using the curves adjustment is to modify the tonal curve. A point is added to the lower half of the tonal curve and that point is dragged down. Another point is added to the upper half of the tonal curve and it is dragged up. This creates an “S” shape and is often referred to as an “S” curve. This curve darkens the shadows and brightens the highlights which increases contrast. Typically increases in contrast improve an image. But as with all tonal adjustments, darkening the shadows and brightening the highlights can result in lost image detail.
As with the levels adjustment the shadows slider is defaults to the darkest point in the image and moving the slider to the right “resets” the darkest point. This will darken the image and increase contrast but detail will be lost in those darkest areas. The highlights slider has the opposite effect, left movement brightens the image but detail is lost in the brightest areas. Areas that might be clipped can be identified by in the same manner as the levels adjustment. Hold down the option key while the sliders are moved to enter threshold display mode. Release the option key to exit threshold display mode.
Slight movement of these two sliders as well as adjusting the tonal curve can have an impact on color, saturation and contrast. Again as image contrast is impacted the apparent sharpness can to be impacted. The curves adjustment is a powerful tool, one that with practice can become invaluable for image adjustments.
I rarely use the exposure adjustment as I find the levels and curves adjustment provide more precision. Below is a brief synopsis of the three sliders and eyedroppers within this adjustment.
The exposure slider targets the image’s highlights. The offset slider targets the shadows and mid-tones and the gamma correction slider targets only the mid-tones. Increases in the values of the these sliders increases brightness to decreases in the values increase darkness.
The three eyedroppers set the black point, white point and middle gray of the image. By moving the eyedropper to a specific area and clicking it, that point will be set for the image. The black eyedropper sets the image’s the black point. This is much like moving the shadows slider in the levels adjustment. The same applies for the white eyedropper, it sets the image’s the white point and the gray eyedropper, sets the image’s the mid-tone point of the image.
In addition to the slider adjustments, the opacity and blending modes can be changed to further fine-tune the these adjustments. The different types of blending mode and there impacts to an image will be discussed in a later post.
While tonal balancing can enhance an image there are some considerations to think about as an image is adjusted. Since brightening highlights or darkening shadows, image detail can be lost. The opposite is also true, by darkening highlights or lightening shadows, image contrast can be lost. In general tonality adjustments do a better job at increasing contrast than reducing contrast. This is where masks become useful. Masks can be used to target specific areas of the image such as lightening dark areas and darkening light areas. Mask creation will be detail in a later post.
Finally extensive brightening of dark areas can and will lead to increased noise. Noise will make the image appear soft so consideration should to exposure at image capture.
Tonality adjustments can have a significant impact on the visual quality of image. With only the above noted adjustments, an image’s color, contrast and apparent sharpness can all be recovered and greatly improved.