A plain-English glossary of imagery terms to help you understand file formats, resolution, cropping, print setup and digital design language.

Imagery plays a major role in how a brand feels, reads and is remembered. The challenge is that image terminology can quickly become technical, especially when conversations move into file formats, resolution, print setup and digital display.

This glossary explains common imagery terms in plain language, so you can work more confidently with designers, printers, developers and marketing teams.

If you are reviewing a project, briefing a designer or preparing brand assets, these terms will help you ask better questions and make clearer decisions.

Imagery glossary terms

Aspect ratio

The proportional relationship between an image's width and height, usually written as two numbers such as 16:9. Aspect ratio affects how visuals are framed, cropped and displayed across screens, adverts, social posts and printed materials.

Bit depth

Bit depth, also known as colour depth, describes how much colour information an image can store. Higher bit depth can support smoother gradients and more accurate colour, which is useful for detailed photography, retouching and high-quality production work.

Bleed

Bleed is the artwork area that extends beyond the final trim line in print. It prevents thin white edges from appearing after cutting and is essential for professional print materials such as brochures, posters and business cards.

Colour mode

Colour mode defines how colour is built in a file. RGB uses red, green and blue light for screens. CMYK uses cyan, magenta, yellow and black ink for print. Choosing the right colour mode helps keep colours closer to what you expect across digital and printed outputs.

Cropping

Cropping means trimming an image to focus attention on a particular area. Good cropping can improve composition, remove distractions and make the most important part of the image easier to understand.

Crop marks

Crop marks are small guide lines that show where printed artwork should be trimmed. They help printers cut the final piece accurately, especially when the artwork includes bleed.

DPI

DPI stands for dots per inch. It is used in print to describe how many ink dots fit into one inch. Higher DPI usually means sharper printed detail, while low DPI can make printed images look soft or pixelated.

GIF

GIF stands for Graphics Interchange Format. It is a raster file format often used for simple animations, icons and low-colour web graphics. GIFs are useful for lightweight movement, but they are not ideal for high-quality photography or detailed brand visuals.

Greyscale

Greyscale uses shades of grey from black to white, without colour information. It can be useful for certain print jobs, accessibility checks, image treatments or designs where contrast and tone are more important than colour.

Hero image

A hero image is a large image usually placed near the top of a webpage. It helps set the tone, communicate the main idea and give visitors an immediate visual signal about the brand, product or message.

JPEG

JPEG stands for Joint Photographic Experts Group. It is a common raster image format that balances image quality and file size through lossy compression. JPEGs are widely used for photography and web imagery, but repeated editing and saving can reduce quality.

Layer mask

A layer mask is a non-destructive editing tool that hides or reveals parts of a layer without permanently deleting the original image. It gives designers more control when blending images, applying effects or refining compositions.

Lossy compression

Lossy compression reduces file size by permanently removing some image data. It can make images easier to store and load, but too much compression can cause visible artefacts and a drop in quality.

Lossless compression

Lossless compression reduces file size while preserving the original image data. It usually creates larger files than lossy compression, but it keeps quality intact.

Monochrome

Monochrome imagery uses one colour, with variations in tone, tint or shade. It can create a calm, focused or refined visual style when used carefully.

PNG

PNG stands for Portable Network Graphics. It is a raster format that supports transparency and lossless compression, making it useful for logos, icons, overlays and other web graphics that need clean edges or transparent backgrounds.

PPI

PPI stands for pixels per inch. It describes pixel density on a screen or in a digital image. Higher PPI can support sharper detail, especially on high-resolution displays.

Raster image

A raster image is made from pixels. Photographs, JPEGs, PNGs and GIFs are common raster formats. Raster images can lose quality when scaled up because the pixels become more visible.

Resolution

Resolution describes the amount of detail in an image, often measured in pixels or through values such as DPI and PPI. Higher resolution usually gives more detail, but it can also create larger files.

Safe zone

The safe zone is the area where important content, such as text and logos, should sit so it does not get cut off during trimming, cropping or display across different formats.

Smart object

A smart object is a Photoshop feature that preserves source image data. It allows designers to resize, transform and apply certain effects without permanently damaging the original image.

Transparency

Transparency allows part of an image or graphic to show what sits behind it. It is often used for logos, overlays, icons and cut-out graphics that need to sit cleanly on different backgrounds.

Vector image

A vector image is created using mathematical paths rather than pixels. Vectors can be scaled up or down without losing sharpness, which makes them ideal for logos, icons and illustrations.

More design glossary terms

If you found this useful, you may also want to read our related design glossary posts.

• Design glossary terms: Essentials
• Design glossary terms: Typography