adobe photoshop cs5 – illustrated unit e: improving images with adjustment layers

Adobe Photoshop CS5 – Illustrated

Unit E: Improving Images with Adjustment Layers

Objectives

Understand grayscale

Investigate a grayscale image

Use the Brightness/Contrast adjustment

Adjust black and white points with levels

Adobe Photoshop CS5 - Illustrated

Objectives

Adjust the midpoint with levels

Investigate an RGB image

Use the Color Balance adjustment

Use the Vibrance adjustment


Improving Images with Adjustment Layers

Images can come from anywhere

Photoshop’s practical operations Improve image characteristics

• Color, contrast, overall effect

Adjustment layer Allows for adjustments applied to image

• Does not directly affect the artwork

Called “non-destructive”• Exists as a layer on the Layers panel


Understanding Grayscale

Grayscale digital image Each pixel: one of 256 shades of gray

256 shades of gray Creates continuous tone image illusion Grayscale range: 0-255

• Pixels grayscale value of zero: black• Pixels grayscale value of 255: white• Any number in between: light to dark gray

128: middle point in the grayscale range



Sampling pixels Identifying pixel information in the info

panels

Info panel displays the Grayscale readouts sample pixels in ink percentages Readout provides information for the

printed image resolution




Info panel settings

Sampling the lightest pixels in the Image

CLASSROOM ACTIVITIES

True/False. A grayscale image refers to a digital image in which each pixel can be one—and only one—of 256 shades of gray.

(Answer: True)

2. Quick Quiz: True/False. Pixels with a grayscale value of 0 are white.

(Answer: False)


Investigating a Grayscale Image

Analyzing image appearance Identify highlights, shadows, midtones

Highlights Lightest image areas Pixels values in upper third of grayscale

range

Shadows Darkest areas Pixels in low third of the grayscale range



Midtones Fall into middle grayscale range

Individual digital image pixels Illusion of continuous tone Smooth transition from shadows to

midtones to highlights

Creation of illusions Requires sufficient number of grays

available per pixel




Shadows, midtones, and highlights identified on the

gradient

Image 3 shades of gray available per pixel

Image with 16 shades of gray available per pixel


True/False. Midtones are the darkest areas represented by pixels in the low third of the grayscale range.

(Answer: False)

Why the number values on the right of the info panel can only be 0, 148, or 255.


Using the Brightness/Contrast Adjustment

Adjustments Operations affecting image appearance

• Manipulating brightness and contrast

Can be made directly to pixels on a layer• Cannot go back and readjust at a later time

Creation of adjustments layers Adjustments existing as layers on the

Layers panel Affect image Can be manipulated at a later time



Adjustment layer Can be hidden, re-shown, deleted at any

time

Brightness/Contrast adjustment Brightness: defined by grayscale value

• Higher the number, the brighter the pixel

Contrast: represented by the relationship between the highlights and shadows• Good when highlights and shadows distinctly

different in tonal range; not “flat”



Key to making adjustments Walk the fine line between going far

enough and going to far with the adjustment

Designers Push adjustment to the extreme

• To see what the adjustment looks like• Can easily see what is not wanted• Can make it easier to make adjustments




Before and after the adjustment

Increasing the brightness


What is brightness?

(Answer: Brightness is defined by a pixel’s grayscale value: the higher the number, the brighter the pixel.)

What is contrast?

(Answer: Contrast is represented by the relationship between the highlights and shadows.)


Adjusting Black and White Points with Levels

Start and end of the image tonal range Black point

• Represents darkest image pixel

White point• Represents brightest image pixel



Black and white points Have substantial effect on contrast

Cameras set to capture image without making too many shadows or highlights that are too white Results provide a smooth tonal range Image still lacks contrast



The Levels adjustment Fixes shadows: not

dark enough Fixes highlights: not

quite white enough Histogram component

• Adjusts image by manipulating sliders at the bottom


Levels adjustment options on the Adjustments panel



Adjustments panel with Levels adjustment layer settings

Adjusting the black and white points


True/False. Every image has a black point.

(Answer: True)

Which point represents the brightest pixel in the image?

(Answer: the white point)


Adjusting the Midpoint with Levels

Midpoint Defines areas of image falling into the

available grayscale range middle

Moving the midpoint lightens or darkens the image Start at the outside and work inwards

• Set black and white points: the extremes

Verify satisfactory contrast between highlight and shadow range

Midpoint can be adjustedAdobe Photoshop CS5 - Illustrated


Adjustment layer creation Created automatically with a layer mask

• Like the Levels adjustment

Layer mask Applies adjustment selectively in different

strengths to different areas of artwork




Masking areas of the image from the adjustment

Masking areas of the image from the adjustment

Brightening the midtones


True/False. You begin with the midpoint.

(Answer: False)

True/False. You can rename a layer.

(Answer: True)


Investigating an RGB Image

Monitors display color as light

Red, green, blue: additive primary colors of light Combine to produce all other colors in

the spectrum Mixing varying strengths produce

yellows, purples, limes, etc. RGB: like grayscale

• Various shades available per pixel• 256 shades of red, green, and blue



Color printing Use cyan, magenta and yellow inks plus

black for detail (CMYK) Different than primary colors for viewing

with a monitor: red, green and blue

Cyan, magenta, and yellow Each created by removing on the

additive RGB primary colors

Photoshop’s color adjustment dialog boxes use RGB and CMY as basis




Viewing the Red channel only

Viewing the image with no red component

Viewing the image with no blue component


Which color is “minus blue”?

(Answer: yellow)

What the additive primary colors of light are. Have them discuss the colors of the spectrum in reference to the additive primary colors.


Using the Color Balance Adjustment

Color Balance Adjustment controlling balance of red,

green and blue in an image Digital camera images often too red

• Fixed using the Color Balance adjustment



Pixel’s red component number Substantially greater than green and blue

number will have a red hue

If numbers for red, green and blue colors are close in value: Pixel becomes neutral in color

If numbers are the same: Pixel will have no color Can only be a neutral gray




Color Balance adjustment



What three colors in an image can you control?

(Answer: red, green, and blue)

True/False. Whites in eyes are a great place to sample for midtones and highlights.

(Answer: True)


Using the Vibrance Adjustment

Vibrance adjustment Useful for quickly making colors in an

image more vibrant Vibrance

• Refers to intensity of a color

Measure of a pixel’s vibrance• Called saturation• High saturation produces vibrant color• Reduced saturation produces dull, more

neutral color• Pixel with no saturation: neutral gray



Vibrance Adjustment settings Saturation

• Increases or decreases saturation value of all pixels selected

Vibrancy• Increases saturation of pixels needing it • Does not affect pixels already saturated




Over saturating the image



What refers to the measure of a pixel’s vibrance?

(Answer: saturation)

True/False. The last state listed in the History panel represents the first change you made to the file.

(Answer: False)


Summary

Photoshop offers practical operations Improve characteristics of images

• Color, contrast, overall effect

Analyzing image appearance first step• Image highlights, shadows, midtones

Digital image• Illusion of continuous tone

Black point: darkest pixel in the image

White point: brightest pixel in image


Summary

Levels adjustment Fixes shadows not dark enough Fixes highlights not quite white enough

Color Balance Adjustment controlling image balance of

red, green and blue

Vibrance adjustment Provides a setting for saturation and

vibrancy


adobe photoshop cs5 – illustrated unit e: improving images with adjustment layers

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