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Glossary
Look up any term from this course. Each entry links back to the lesson that taught it.
| Term | Definition | Lesson |
|---|---|---|
| Bit depth | The number of bits used to store the colour of each pixel (or of each colour channel). More bits allow more possible colours or shades. | Bit Depth |
| CMYK colour mode | A subtractive colour model that makes colours by printing cyan, magenta, yellow and black (K) inks on paper; used for commercial printing. | Colour Modes: RGB and CMYK |
| Compression artefacts | Visible faults caused by lossy compression, such as blocky squares, blurred edges and 'halo' specks around text. | Lossy and Lossless Compression |
| dpi (dots per inch) | The number of ink dots a printer places in each inch; often confused with ppi. | Pixels and Resolution |
| Gamut | The range of colours a device or colour mode can reproduce; colours outside it are 'out of gamut'. | Colour Modes: RGB and CMYK |
| Lossy / lossless compression | Lossy compression discards some detail to make files much smaller (JPG); lossless keeps every pixel exactly (PNG, TIFF). | Lossy and Lossless Compression |
| Pixel | The smallest element of a digital raster image: a tiny square of a single colour. Images are grids of pixels arranged in rows and columns. | Pixels and Resolution |
| Pixel dimensions | The number of pixels across and down an image, e.g. 3508 × 4961 px. | Pixels and Resolution |
| PSD | Photoshop's own file format, which keeps layers, masks, text and effects editable. | Image File Formats |
| Raster graphic | An image made of a grid of pixels, such as a photograph. | Raster and Vector Graphics |
| Resampling | Changing the number of pixels in an image; enlarging invents new pixels and reduces sharpness. | Image Size and Print Size |
| Resolution (ppi) | The number of pixels per inch (ppi) when an image is printed or displayed at a particular physical size. | Pixels and Resolution |
| RGB colour mode | An additive colour model that makes colours by mixing red, green and blue light; used by screens, cameras and the web. | Colour Modes: RGB and CMYK |
| Vector graphic | An image made of mathematical shapes that stay sharp at any size, such as a logo in SVG format. | Raster and Vector Graphics |
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