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How to write alt text, produce accessible diagrams, choose images and copyright standards for GOV.UK. Where possible, publish your diagrams using the SVG image format - this will allow users to zoom in and out.
The basics
Sizes required
Images must be 960 x 640 pixels in dimension to be used on GOV.UK. This is a landscape orientation.
Images should be a minimum of 72 dpi (dots per inch).
Pixel meaning
A pixel (a word invented from 'picture element') is the basic unit of programmable colour on a computer display or in a computer image. Think of it as a logical, rather than a physical, unit of measurement.
No special design skills needed
You don't need graphic design skills or software to resize images to the required specifications.
General tips
Give your image a descriptive file name. Avoid meaningless file names like IMG00023.jpg.
Avoid putting borders around images. The image should go right to the edge of the frame.
Read the image copyright standards on when you should attribute your image.