22-3530 - 01 PHOTO COMMUNICATIONS

of pixels and bits

Measuring pixels

VECTOR IMAGES

Based on points & paths, numericalResolution independent

RASTER IMAGES (bitmap)

A mosaic of pixels (picture elements)Resolution dependent

Raster = Resolution Dependent

1430 pixels

1132 pixels

Each raster image is made of a speci!c number of pixels (pixel dimensions)

IMAGE DETAIL

Every time you capture a digital image, you create a speci!c number of pixels. Image detail is translated into differences

between pixels that the camera registers at the time of capture. Increasing resolution degrades the true detail from

the capture with a ‘best guess’ (interpolation).

VIEW PERCENTAGE

1430 x 1132 1024 x 768

View percentage at 100%

View percentage at 60%

Every raster image contains a certain number of pixels. Every pixel contains a certain number of bits (ones or zeroes).

The number of bits contained in each pixel is called the image’s bit depth.

BIT DEPTH

for example,

If you are working with an 8-bit grayscale image, each pixel contains 8 zeroes or ones.

2 = 01010101 = 2568

8 BIT vs (12 vs) 16 BIT

File size is directly connected to the number of bits contained in an image. For example,

BIT DEPTH AND FILE SIZE

8 bits = a byte

If an 8-bit grayscale image has a pixel dimension of:1430 x 1132 = 1618760 pixels

1 kilobyte = 1024 bytes1 megabyte = 1024 kilobytes

1618760 divided by 1024 (a kilobyte) = 1580.821580 divided by 1024 (a megabyte) = 1.54

IMAGE SIZE WINDOW

Three different ways of describing image size:

1. Image size2. Pixel dimensions (count)3. Document size: how the pixels are distributed in the “real world,” i.e., your printer

Tone

LEVELS

Hi-contrast Lo-contrast

HISTOGRAMS EVERYWHERE

TONAL KEY

Tonal character can be de!ned in terms of light, dark, or average, or use the terms high, low, and medium key.

high key medium key low key

DESTRUCTIVE EDITS

All tonal edits “damage” the !le to some extent. Extreme edits to tone using levels or curves can leave large tonal ranges completely

empty. These gaps in the histogram create what is called banding or posterization.

NON-DESTRUCTIVE EDITS

Using adjustment layers allows you to make tonal adjustments without permanently deleting capture data.

SHADOW AND HIGHLIGHT

Be sure to always keep an eye on maintaining shadow and highlight detail when making tonal edits.

for !lm: Expose for the shadows and develop for highlightsfor digital: Expose for highlights (most of the time)

BLOWN OUTHIGHLIGHTS

PLUGGEDSHADOWS

CURVES

Curves allows you to focus your corrections more accurately within the histogram than Levels.

BRIGHTNESS/CONTRAST ADJUSTMENTS

SHADOW & HIGHLIGHT TOOL

Pixel quality control

Finding design patternsSHOOTING ASSIGNMENT #2

Line

Shape

Texture

Space

Size

Value

L I N ELines can organize, direct, separate, be expressive, suggest emotion, or create rhythm. They can join elements or divide them using a rule, which is a line that separates one element in a design from another.

S H A P EThe external outline of a form or anything that has height and width. An example would be the three basic shapes: the circle, the square, and the triangle, considered to be the fundamental shapes found in all design.

T E X T U R EThe look and feel of a surface. In two-dimensional form, texture is essentially visual and adds richness and dimension to work. Texture can also refer to pattern, which is visual texture.

S P A C ERefers to the distance between shapes and forms, but it is best understood in design as white space or negative space—terms used to refer to the empty but often active areas that are void of visual elements.

S I Z EHow big or small something is in scale to other objects. Scale refers to the process of making size relationships. unless there is a scale of reference within a design, it is impossible to discern the relative scale of objects and the meaning they represent.

VALUE (& COLOR)The relative lightness or darkness of an area or object. Value adds dimension by creating the illusion of depth in a design. With the addition of a color, you can create and convey a mood to enhance a strong concept.