Adjust image tonal range & colour values using imaging software
1. Outline the steps to adjust image’s tonal range and colour
values using imaging software.
2. In This Chapter, you’ll learn on:
Identify the tools that manipulates the following:
o colour levels
o brightness
o contrast
o shadows
o mid-tones
o highlights
Adjust the image’s colour levels, brightness, contrast
and highlights to improve its aesthetic appeal.
3. Colour and tonal adjustments
There are powerful tools in Photoshop that can enhance,
repair, and correct the colour and tonality (lightness, darkness,
and contrast) in an image. Most of the adjustments is
accessible via Image > Adjustments. However we are
introducing adjustments via layers.
To do this,
go to Layers > New Adjustment Layer or
4. Colour and tonal adjustments
Select which adjustment you need on the on the layers palette
(accessible in Window/ Adjustment)
5. Colour and tonal adjustments
It will create an additional layer that contains the adjustment
while preserving the original image.
6. Colour and tonal adjustments
The adjustment panel will switch to a new layer with sliders
controls for you to fine tune your settings to your image. Some
of the common tools for tonal and colour adjustments are
“Brightness/Contrast”, “Levels”, “Curves”, “Vibrance”,
“Hue/Saturation”, and “Colour balance”.
Original Image before adding any adjustment layers
7. Colour and Tonal Adjustment: Brightness / Contrast
The Brightness/Contrast adjustment lets you make simple adjustments
to the tonal range of an image. Moving the brightness slider to the
right increases tonal values and expands image highlights, to the left
decreases values and expands shadows. The contrast slider expands
or shrinks the overall range of tonal values in the image.
By adjusting the brightness and contrast, you can make the picture brighter
8. Colour and Tonal Adjustment: Levels
The outer two Input Levels sliders map the black point and white point to the settings of the
Output sliders. By default, the Output sliders are at level 0, where the pixels are black, and
level 255, where the pixels are white. With the Output sliders in the default positions, moving
the black input slider maps the pixel value to level 0 and moving the white point slider
maps the pixel value to level 255. The remaining levels are redistributed between levels 0
and 255. This redistribution increases the tonal range of the image, in effect increasing the
overall contrast of the image.
By adjusting the levels, you can also increase the overall contrast between the
black and white
9. Colour and Tonal Adjustment: Curves
Using curves to obtain colour balance is best for global colour
shifts because it compresses/stretches the tonal values across
the image. In other words, it achieves an over-all shift in the
shadows, midtones, and highlights. For colour correction in a
specific tonal range you can use the Colour Balance tool.
Adjusting the curves achieve an overall midtones/shadows/highlights shifting
10. Colour and Tonal Adjustment: Vibrance
Vibrance adjusts the saturation so that clipping is minimized as
colours approach full saturation. This adjustment increases the
saturation of less-saturated colours more than the colours that
are already saturated. Vibrance also prevents skintones from
becoming over saturated.
Adjusting the Vibrance can make the colours of the image richer or vice
versa.
11. Colour and Tonal Adjustment: Hue / Saturation
Hue/Saturation lets you adjust the hue, saturation, and lightness
of a specific range of colours in an image or simultaneously
adjust all the colours in an image. This adjustment is especially
good for fine-tuning colours in a CMYK image so that they are
in the gamut of an output device.
Adjusting the hue/saturation can also help create special colour cast/effects.
12. Colour and Tonal Adjustment: Colour Balance
Colour Balance is a general term referring to the fine balancing of the colours in visible light
and it is strongly tied to the white balance. White Balance refers specifically to the way the
Colour Balance is adjusted so white objects will appear white under any lighting conditions.
The human eye is well adapted, in connection with our brains, to adjust the colour
information it receives so that objects we know to be white, appear white. If this did not
happen, and we processed light as it is, "white" objects would look yellow under tungsten
light, green under fluorescents, etc.
By adjusting the colour balance, you can alter the white balance to give the
image a different look.