ICDL Image Editing (ICDL) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Raster image

A raster image stores picture information as a rectangular grid of pixels; each pixel has color values, so enlarging beyond native dimensions requires interpolation and may reduce sharpness.

Vector image

A vector image represents shapes with mathematical paths, points, and attributes; it can be scaled without pixelation until rasterized into a pixel grid for display or output.

Image resolution

Image resolution usually means pixel dimensions, width by height; PPI relates those pixels to a physical inch when printing and does not change the stored pixel count.

Color depth

Color depth is the number of bits used per pixel or channel; 8 bits per channel gives 256 levels, while 24-bit RGB can represent about 16.7 million color combinations.

Alpha channel

An alpha channel stores transparency separately from color channels; compositing blends foreground and background according to alpha, with zero fully transparent and one fully opaque.

Histogram

A histogram graphs the number of pixels at each tonal level; it shows distribution and clipping but contains no information about where those tones are located spatially.

RGB color model

The RGB model is additive: red, green, and blue light combine to make white. It is used for displays and scanners; numeric values typically range from 0 to 255 per channel.

Exposure triangle

The exposure triangle links aperture, shutter speed, and ISO. Changing any one alters exposure; aperture also changes depth of field, shutter speed changes motion blur, and ISO changes noise.

Aperture f-number

An f-number equals focal length divided by effective aperture diameter. Smaller numbers mean wider apertures and less depth of field; each full stop doubles or halves light.

Shutter speed

Shutter speed is the duration the sensor is exposed. Halving the time, such as 1/125 second instead of 1/60 second, halves exposure and generally reduces motion blur.

ISO sensitivity

ISO setting controls amplification of the sensor signal. Raising ISO brightens exposure for a given aperture and shutter speed but typically increases visible noise and reduces dynamic range.

White balance

White balance adjusts color rendering so neutral subjects appear neutral under different light. Daylight is roughly 5500 K, tungsten about 3200 K, and shade higher than daylight.

Optical scanner resolution

Optical scanner resolution is the true sampling rate determined by the sensor and optics, expressed in ppi; interpolated resolutions add estimated pixels and do not create new detail.

Canvas size

Canvas size changes the working area without resampling existing pixels; enlarging adds space, while reducing crops content. Image size, by contrast, can resample pixel dimensions.

Layer mask

A layer mask controls visibility without deleting pixels. In a standard grayscale mask, black hides, white reveals, and intermediate gray values produce partial transparency.

Adjustment layer

An adjustment layer applies color or tonal changes non-destructively; it affects layers beneath it and can be edited, masked, or removed without altering original pixel data.

Feathering

Feathering softens a selection edge by creating a gradual transition between selected and unselected areas; a larger feather radius produces a wider, smoother boundary.

Blend mode

A blend mode determines how a layer's pixels combine with pixels below, such as Multiply darkening or Screen lightening; opacity controls the strength of that combination.

Vector path

A vector path is defined by anchor points and curve segments. It can be edited, converted to a selection, or used as a mask without depending on image pixel resolution.

Cropping

Cropping removes pixels outside a chosen boundary, reducing image dimensions and changing composition; it cannot restore detail that was outside the original frame.

Resampling

Resampling changes the number of image pixels by interpolation. Downsampling discards pixels and can reduce detail; upsampling estimates new pixels and cannot recover true detail.

Clone stamp

The clone stamp copies pixels from a sampled source point to a destination point. It preserves source texture and color, making source alignment and edge softness important.

Healing brush

The healing brush copies texture from a sampled source while blending color and luminosity with surrounding pixels, making repairs blend better than a hard clone in many retouching tasks.

Unsharp mask

Unsharp mask sharpens by increasing contrast at edges. Amount controls strength, radius controls edge width, and threshold sets how different neighboring tones must be before sharpening applies.

Levels adjustment

A Levels adjustment remaps input tones to output tones using black point, gamma midpoint, and white point controls; it can correct contrast and cast while showing a histogram.

Smart object

A smart object stores source data and transformation settings non-destructively; repeated scaling, filters, and edits can be adjusted later without permanently resampling the original pixels.

JPEG format

JPEG uses lossy compression, typically 8-bit, and does not support alpha transparency. Higher quality settings preserve more detail but create larger files; repeated saving can accumulate artifacts.

PNG format

PNG is a lossless raster format supporting alpha transparency and indexed or truecolor images. It suits graphics, screenshots, and web images where sharp edges and transparency matter.

TIFF format

TIFF is a flexible raster container often used for print and archiving; it can be lossless, support layers or alpha, and preserve high bit depth, but files are usually large.

ICC profile

An ICC profile describes a device's color behavior so color-management software can convert between color spaces; embedding a profile helps others interpret image colors correctly.

Print resolution formula

Printed size in inches equals pixel dimensions divided by output ppi. For example, 3000 pixels at 300 ppi produces 10 inches; changing ppi changes print size unless resampling occurs.

Lossy compression

Lossy compression reduces file size by discarding some image data, often imperceptible at moderate settings. Repeated editing and resaving can compound artifacts, especially in JPEG workflows.