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ICDL Image Editing study materials
ICDL Image Editing study resources

ICDL Image Editing (ICDL) practice questions

One question at a time. Build your ICDL Image Editing understanding.

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Question 1Imaging Concepts

Which term describes an image built from a grid of individual pixels?

  1. Raster Correct answer.
  2. Path
  3. Metafile
  4. Vector

Explanation

Raster (bitmap) images are made of a fixed grid of pixels, and each pixel stores colour values. Vector graphics instead describe shapes mathematically with points and paths. Metafiles are containers that may hold either kind of data.

Question 2Imaging Concepts

A digital image has pixel dimensions of 3000 × 2000. Approximately how many megapixels is that?

  1. 6 megapixels Correct answer.
  2. 12 megapixels
  3. 3 megapixels
  4. 9 megapixels

Explanation

Multiply the width by the height: 3000 × 2000 = 6,000,000 pixels. One megapixel is one million pixels, so the image is 6 megapixels.

Question 3Imaging Concepts

Which file format uses lossy compression and is well suited to photographs?

  1. SVG
  2. TIFF
  3. PNG
  4. JPEG Correct answer.

Explanation

JPEG uses lossy compression, discarding some visual data to achieve small files, which suits photographs. PNG and TIFF are typically lossless, and SVG is for vector graphics.

Question 4Imaging Concepts

Which colour mode is the standard choice for a document that will be printed with process inks?

  1. RGB
  2. CMYK Correct answer.
  3. Grayscale
  4. Indexed colour

Explanation

CMYK is the subtractive colour model used by most printing presses, with cyan, magenta, yellow and black inks. RGB is intended for screens and light-based output.

Question 5Imaging Concepts

What does dots per inch (DPI) describe in image editing?

  1. The number of pixels in an image's width and height
  2. The number of printer ink dots per inch Correct answer.
  3. The number of frames stored per second
  4. The number of colours an image can contain

Explanation

DPI measures how many ink dots a printer places along one inch of printed output. Pixel dimensions describe the image grid, while bit depth determines the number of colours.

Question 6Imaging Concepts

An image measures 1920 × 1080 pixels. Which aspect ratio does it have?

  1. 16:9 Correct answer.
  2. 1:1
  3. 3:2
  4. 4:3

Explanation

Divide both dimensions by their greatest common divisor: 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9. The ratio is therefore 16:9, a common widescreen format.

Question 7Imaging Concepts

An 8-bit grayscale image can represent how many different shades?

  1. 1024
  2. 8
  3. 64
  4. 256 Correct answer.

Explanation

An 8-bit channel can hold 2^8 = 256 different values. In grayscale mode those values run from black to white.

Question 8Imaging Concepts

Which channel stores per-pixel transparency information in an image?

  1. Saturation channel
  2. Alpha channel Correct answer.
  3. Hue channel
  4. Luminance channel

Explanation

The alpha channel stores per-pixel transparency, allowing an image to blend with whatever lies behind it. Hue, saturation and luminance describe colour, not opacity.

Question 9Imaging Concepts

In an RGB image, what is produced when red, green and blue are all set to their maximum value?

  1. Cyan
  2. Black
  3. Gray
  4. White Correct answer.

Explanation

RGB is an additive model: red, green and blue light combine at full strength to produce white. Turning all channels to zero produces black.

Question 10Imaging Concepts

Why should a JPEG photograph be edited and saved repeatedly with caution?

  1. The file is converted to a vector format after several saves.
  2. Each save recompresses the image and may discard more detail. Correct answer.
  3. The alpha channel is removed every time the file is saved.
  4. The colour mode changes from RGB to CMYK automatically.

Explanation

JPEG is a lossy format, so each save re-encodes the image and can throw away more data. Repeated editing and saving can produce visible artifacts. Keeping a lossless master avoids this.

Question 11Imaging Concepts

A company logo must stay sharp on a billboard and on a business card. Which file type is most suitable?

  1. A vector file defining the logo with paths Correct answer.
  2. A high-resolution JPEG photograph of the logo
  3. A GIF version of the logo with a limited palette
  4. A bitmap image saved at 72 ppi

Explanation

Vector files define shapes with paths, so they can be enlarged to billboard size without pixelation. Bitmap images are tied to a fixed pixel grid and lose sharpness when scaled up.

Question 12Imaging Concepts

What is a colour gamut?

  1. The number of layers an image can contain
  2. The range of colours a device can reproduce Correct answer.
  3. The largest file size a format can store
  4. The speed at which an image is rendered

Explanation

A gamut is the range of colours a particular device, such as a monitor or printer, or a colour space can represent. Colours outside that range are called out of gamut.

Question 13Imaging Concepts

An image is 4000 × 3000 pixels and the file is too large for a website. Which change reduces file size while keeping the same pixel dimensions?

  1. Increasing the colour bit depth
  2. Adding an alpha channel
  3. Converting to an uncompressed TIFF
  4. Lowering the JPEG quality setting Correct answer.

Explanation

The JPEG quality setting controls how much lossy compression is applied; lowering it reduces file size at the cost of image detail. Changing to uncompressed TIFF or adding data would increase file size.

Question 14Imaging Concepts

A photo will be printed at 300 ppi and must measure 6 × 4 inches. What minimum pixel dimensions are needed?

  1. 1200 × 800
  2. 1800 × 1200 Correct answer.
  3. 2400 × 1600
  4. 3000 × 2000

Explanation

Multiply each printed dimension by the required ppi: 6 × 300 = 1800 pixels wide and 4 × 300 = 1200 pixels high. So the minimum is 1800 × 1200 pixels.

Question 15Imaging Concepts

A 24-bit RGB image uses 8 bits per channel. How many colours can it represent?

  1. 4,294,967,296
  2. 65,536
  3. 16,777,216 Correct answer.
  4. 256

Explanation

A 24-bit image has 2^24 possible colour values, which equals 16,777,216. This is often described as about 16.7 million colours.

Question 16Imaging Concepts

Which statement describes an indexed-colour image?

  1. Tones are stored only as 8-bit grayscale values.
  2. Each pixel stores its own full 24-bit colour value.
  3. Colours are defined by mathematical paths.
  4. Pixels refer to entries in a limited colour table. Correct answer.

Explanation

In indexed colour, each pixel stores an index into a colour table, so the palette size limits the colours available. GIF is a common indexed format with up to 256 entries.

Question 17Imaging Concepts

Which format stores vector graphics as XML text that can be scaled without losing quality?

  1. SVG Correct answer.
  2. JPEG
  3. PNG
  4. TIFF

Explanation

SVG is an XML-based vector format, so shapes and text are stored as instructions rather than pixels. This allows clean scaling to any size.

Question 18Imaging Concepts

What is typically stored in the EXIF metadata of a digital photograph?

  1. The printer's colour gamut
  2. Camera settings and capture information Correct answer.
  3. The vector paths used to draw the image
  4. The individual pixel colour values

Explanation

EXIF metadata records details such as camera model, exposure time, aperture and capture date. It does not store the pixel values themselves or printer characteristics.

Question 19Imaging Concepts

Why can some bright RGB colours look duller after conversion to CMYK for print?

  1. CMYK uses more bits per channel than RGB.
  2. CMYK images cannot contain black.
  3. The conversion increases the image's resolution.
  4. Those colours lie outside the CMYK gamut. Correct answer.

Explanation

CMYK has a smaller gamut than RGB, so very saturated screen colours may be outside what inks can reproduce. Conversion maps them to the nearest printable colour, which can look duller.

Question 20Imaging Concepts

What does a histogram of an image show?

  1. The physical print size at 300 dpi
  2. The file size of each layer
  3. How pixels are distributed across tonal levels Correct answer.
  4. The number of colours in the active palette

Explanation

A histogram plots how many pixels fall at each tonal level, from shadows through midtones to highlights. It helps judge exposure and contrast rather than showing physical size.

Question 21Imaging Concepts

Which resampling method is best for enlarging pixel art while keeping hard edges crisp?

  1. Lanczos
  2. Bicubic
  3. Nearest neighbour Correct answer.
  4. Bilinear

Explanation

Nearest neighbour assigns each new pixel the colour of the closest original pixel, so hard edges stay sharp. Bicubic, bilinear and Lanczos average nearby pixels and tend to blur pixel art.

Question 22Imaging Concepts

A 1200 × 800 pixel image is resized to a width of 600 pixels while keeping its aspect ratio. What should the new height be?

  1. 600 pixels
  2. 300 pixels
  3. 400 pixels Correct answer.
  4. 800 pixels

Explanation

The original ratio is 1200:800, or 3:2. Scaling the width to 600 means dividing by 2, so the height must also be divided by 2, giving 400 pixels.

Question 23Imaging Concepts

An uncompressed 24-bit RGB image measures 1000 × 1000 pixels. Approximately how large is its raw pixel data?

  1. 6 MB
  2. 3 MB Correct answer.
  3. 1 MB
  4. 2 MB

Explanation

A 24-bit pixel uses 3 bytes, one per RGB channel. One million pixels × 3 bytes = 3,000,000 bytes, approximately 3 MB before any file-format overhead.

Question 24Imaging Concepts

What is the purpose of an ICC profile?

  1. To compress an image without losing data
  2. To define the pixel dimensions for printing
  3. To record the camera settings used for a photo
  4. To describe how a device interprets colour values Correct answer.

Explanation

An ICC profile describes the colour characteristics of a device or colour space so that colour management can translate values consistently. It helps keep colours closer across monitors, printers and files.

Question 25Imaging Concepts

When reducing an image to a small indexed palette, what does dithering do?

  1. Sharpens edges by increasing local contrast
  2. Converts the image from RGB to CMYK
  3. Mixes pixels of available colours to simulate missing shades Correct answer.
  4. Removes all transparency from the image

Explanation

Dithering uses patterns of available palette colours so the eye perceives intermediate shades that are not actually present. It reduces banding when the palette is small.

Question 26Imaging Concepts

Which statement accurately distinguishes raster images from vector images?

  1. Raster images store only text, while vector images store only photographs.
  2. Raster images always have larger file sizes than vector images of the same content.
  3. Raster images use mathematical paths, while vector images are built from a grid of pixels.
  4. Raster images use pixels; vector images use mathematical paths. Correct answer.

Explanation

A raster image describes colours on a rectangular grid of pixels, so its appearance depends on resolution. A vector image describes shapes with geometric instructions such as paths and curves, so it can be scaled without pixelation. The distinction concerns how image data is represented, not file size in every case.

Question 27Imaging Concepts

An image has fixed pixel dimensions. If it is printed at a lower ppi setting, what happens to the printed output?

  1. The printed image becomes physically larger while using the same pixels. Correct answer.
  2. The printed image keeps the same size but loses half of its pixels.
  3. The printed image becomes sharper because more pixels fit into each inch.
  4. The printed image becomes physically smaller because each pixel is reduced.

Explanation

PPI expresses how many image pixels are placed in each printed inch. With pixel dimensions unchanged, lowering PPI spreads those pixels over more inches, increasing print size and reducing pixel density. It does not remove pixels from the file.

Question 28Imaging Concepts

Which colour model is subtractive and is used primarily for printing with inks?

  1. HSL
  2. RGB
  3. Lab
  4. CMYK Correct answer.

Explanation

CMYK is subtractive because cyan, magenta, yellow and black inks absorb parts of white light and reflect others. RGB is additive and is used for light-emitting displays. HSL is a way to describe colours, and Lab is a device-independent colour space rather than an ink model.

Question 29Imaging Concepts

A screenshot contains sharp interface text, flat colours and a transparent logo area. Which format is most suitable for saving it for web use?

  1. JPEG, because it discards fine detail to reduce size
  2. GIF, because it is limited to 256 colours and supports simple animation
  3. PNG, because it is lossless and supports an alpha channel Correct answer.
  4. BMP, because it stores pixels without compression

Explanation

PNG preserves sharp edges and flat colours without lossy artifacts and supports transparency through an alpha channel. These properties suit screenshots and interface graphics. JPEG is better for continuous-tone photographs, while GIF and BMP have other limitations.

Question 30Imaging Concepts

What is the defining property of lossless image compression?

  1. The original pixel data can be reconstructed exactly. Correct answer.
  2. Colour information is discarded while brightness is kept.
  3. The file is always smaller than any lossy version.
  4. Only photographic images can be compressed this way.

Explanation

Lossless compression reduces file size while allowing the exact original data to be restored when the file is opened. It does not discard image information permanently. Lossy compression, by contrast, removes some data to achieve smaller sizes.

Question 31Imaging Concepts

An image is 800 × 600 pixels. The canvas is extended to 1000 × 600 without resampling the existing content. What is the result?

  1. The existing content is stretched horizontally to fill the new width.
  2. The image resolution increases to 1000 ppi automatically.
  3. The existing content keeps its size and blank space is added at the sides. Correct answer.
  4. The existing content is cropped to 800 × 600 with no change.

Explanation

Changing canvas size alters the available work area without scaling the existing pixels. Extending the canvas creates additional empty space around the original content. Resampling would be required to stretch or shrink the image content itself.

Question 32Imaging Concepts

A photo taken indoors under tungsten lighting looks strongly orange. Which adjustment best corrects this?

  1. Increasing the image's saturation
  2. Converting the image to grayscale
  3. Applying a strong sharpening filter
  4. Setting a white balance suitable for tungsten light Correct answer.

Explanation

White balance compensates for the colour temperature of the light source so neutral objects appear neutral. A tungsten setting cools the image to offset the orange cast. Saturation and sharpening affect colour intensity or edge contrast rather than the overall cast.

Question 33Imaging Concepts

Which adjustment makes the colours in an image more vivid while leaving their basic hues unchanged?

  1. Rotating the hue by 180 degrees
  2. Increasing the saturation Correct answer.
  3. Reducing the bit depth to 8 bits
  4. Applying a Gaussian blur

Explanation

Saturation controls how pure or intense a colour appears while its hue remains the same. Raising saturation makes colours more vivid. Hue rotation, bit-depth reduction and blur affect different image properties.

Question 34Imaging Concepts

What does a typical sharpening filter do to an image?

  1. It reduces the number of colours used in the image.
  2. It physically adds new detail that was not captured originally.
  3. It boosts local contrast along edges. Correct answer.
  4. It removes all noise from flat areas of the image.

Explanation

Sharpening increases contrast between adjacent tones near edges, creating an impression of greater clarity. It works with detail already present in the image. It cannot recover information that was never captured.

Question 35Imaging Concepts

Why can smooth gradients develop visible bands after an image is converted to a much lower bit depth?

  1. Fewer available tonal levels make small shade changes jump in steps. Correct answer.
  2. The image's aspect ratio changes when bit depth is reduced.
  3. The image loses its metadata during conversion.
  4. All colour channels are merged into a single grayscale channel.

Explanation

Lower bit depth provides fewer discrete levels for representing tone. A smooth gradient must then be approximated with larger jumps between shades, producing visible bands, a effect called posterization. Metadata, aspect ratio and channel merging are separate issues.

Question 36Imaging Concepts

Which statement correctly distinguishes ppi from dpi?

  1. PPI counts printer ink dots, while DPI counts image pixels.
  2. DPI measures how many pixels a camera sensor captures, while PPI measures the monitor's refresh rate in hertz.
  3. PPI and DPI are identical terms for screen resolution.
  4. PPI is image pixels per inch; DPI is printer dots per inch. Correct answer.

Explanation

PPI describes the density of image pixels when displayed or printed. DPI describes how many ink dots a printing device can place in one inch. The terms are related but refer to different parts of the imaging chain.

Question 37Imaging Concepts

A photographer wants colours to appear as consistently as possible on ordinary web browsers. Which colour space is the usual choice?

  1. Lab with a very wide gamut
  2. CMYK
  3. Grayscale
  4. sRGB Correct answer.

Explanation

sRGB is the standard colour space for web graphics and is widely supported by browsers and consumer displays. Using it reduces unexpected colour shifts when an image is viewed online. CMYK is intended for print, Lab is not normally used directly for web display, and grayscale removes colour.

Question 38Imaging Concepts

What is the purpose of anti-aliasing in a digital image?

  1. To remove every compression artifact from a JPEG file.
  2. To convert vector artwork into a lower resolution raster image.
  3. To soften jagged edges by blending boundary pixels. Correct answer.
  4. To increase the colour bit depth of the image.

Explanation

Anti-aliasing reduces the stair-step appearance of diagonal and curved edges by blending boundary pixels with nearby tones. This makes edges appear smoother at normal viewing size. It does not repair compression artifacts or change bit depth.

Question 39Imaging Concepts

Which file type is commonly chosen for lossless editing and archival of high-quality photographs?

  1. TIFF Correct answer.
  2. GIF
  3. JPEG
  4. SVG

Explanation

TIFF is widely used for archival and editing workflows because it can store image data without lossy compression. This helps preserve quality through repeated editing stages. JPEG is lossy, GIF has a limited palette, and SVG is intended for vector graphics.

Question 40Imaging Concepts

Why does enlarging a photograph with interpolation usually fail to recover fine detail that was not captured?

  1. Interpolation compresses the file so that high-frequency data is lost.
  2. It estimates new pixels from existing data rather than creating real detail. Correct answer.
  3. Interpolation converts the photograph into a vector graphic.
  4. Interpolation deletes the image's colour profile.

Explanation

Interpolation calculates new pixel values by examining surrounding existing pixels. It can make an enlarged image look smoother, but it cannot supply information that the original capture never recorded. Genuine additional detail must come from a higher-resolution source.

Question 41Image Capture

What does ppi measure in a digital image?

  1. The number of image pixels per inch Correct answer.
  2. The number of colours per inch
  3. The number of ink droplets per inch
  4. The number of bits per inch

Explanation

Pixels per inch describes pixel density: how many image pixels are assigned to each inch of a printed or displayed output. A higher ppi value packs more pixels into the same physical length, so fine detail is reproduced better. It relates to pixel count and output size rather than ink coverage, colour count or bit depth.

Question 42Image Capture

Which file format is most suitable for a continuous-tone photograph when a small file size matters more than perfect pixel accuracy?

  1. GIF
  2. JPEG Correct answer.
  3. PNG
  4. SVG

Explanation

JPEG applies lossy compression designed for photographic content, discarding subtle detail that viewers are unlikely to notice and producing compact files. PNG is lossless and therefore much larger for photographs. GIF is restricted to 256 colours, and SVG is a vector format unsuitable for photographic capture.

Question 43Image Capture

Which colour model do most digital cameras use to record colour?

  1. Pantone
  2. HSL
  3. RGB Correct answer.
  4. CMYK

Explanation

Camera sensors and most displays work with additive red, green and blue channels, so images are captured and stored in RGB. CMYK is a subtractive model used for ink-based printing. HSL is a way of describing colour relationships, and Pantone is a proprietary spot-colour matching system.

Question 44Image Capture

A camera described as having a 12-megapixel sensor records approximately how many pixels?

  1. 1,200
  2. 12,000
  3. 1,200,000
  4. 12,000,000 Correct answer.

Explanation

One megapixel equals one million pixels, so 12 megapixels is about 12,000,000 pixels in total. This figure is the product of the sensor's pixel width and height. The other values correspond to far smaller or differently scaled counts.

Question 45Image Capture

Which type of zoom preserves image quality best when magnifying a distant subject?

  1. Crop-based zoom
  2. Optical zoom Correct answer.
  3. Interpolated zoom
  4. Digital zoom

Explanation

Optical zoom changes the focal length of the lens, so the subject is magnified before the light reaches the sensor and full sensor resolution is used. Digital zoom simply enlarges a central portion of the frame by cropping and interpolating, which loses real detail. Therefore optical zoom gives the sharpest result.

Question 46Image Capture

An image that is 3000 pixels wide and 2000 pixels high has which aspect ratio?

  1. 4:3
  2. 1:1
  3. 16:9
  4. 3:2 Correct answer.

Explanation

Aspect ratio compares width with height, so 3000:2000 simplifies by dividing both values by 1000 to give 3:2. The same ratio results from any dimensions with width equal to 1.5 times the height. 4:3, 16:9 and 1:1 would give different height values for a 3000-pixel width.

Question 47Image Capture

What is the main purpose of a camera's white balance setting?

  1. To increase the sensor's pixel count
  2. To compress the file before saving
  3. To set the shutter speed for the scene
  4. To compensate for the colour of the light source Correct answer.

Explanation

Different light sources have different colour temperatures, which produce a colour cast if left uncorrected. White balance tells the camera which tones should appear neutral so that other colours render naturally. It does not affect exposure time, file compression or resolution.

Question 48Image Capture

Which type of information is typically stored in a photograph's EXIF data?

  1. An unread EXIF orientation tag Correct answer.
  2. Severe corruption of the file data
  3. Lossy recompression of the image
  4. A missing or incorrect colour profile

Explanation

EXIF is metadata written by the camera at the moment of capture. It commonly records shutter speed, aperture, ISO, focal length, date and time, and an orientation flag. Image editing software can read these values and rotate the picture automatically.

Question 49Image Capture

A 4 by 6 inch photographic print is scanned at 300 ppi. What are the pixel dimensions of the resulting scan?

  1. 600 by 900 pixels
  2. 1200 by 1800 pixels Correct answer.
  3. 300 by 450 pixels
  4. 2400 by 3600 pixels

Explanation

Multiply each physical dimension by the scanning resolution: 4 inches times 300 ppi gives 1200 pixels, and 6 inches times 300 ppi gives 1800 pixels. Scanning at a higher ppi would increase both pixel counts proportionally. The scanned area is unchanged, only its pixel density.

Question 50Image Capture

An uncompressed RGB image measures 2000 by 1500 pixels with 8 bits per channel. Approximately how large is the raw pixel data?

  1. About 3 MB
  2. About 9 MB Correct answer.
  3. About 36 MB
  4. About 24 MB

Explanation

The image contains 2000 times 1500, which is 3,000,000 pixels. At 8 bits per channel and three channels, each pixel needs 3 bytes, giving about 9,000,000 bytes or roughly 9 MB. This estimate ignores headers and any compression applied when saving.