© Sofia Katsikadi - 2017 - Princes Gardens, Edinburgh

Digital images are made up of thousands of pixels, and the amount of them determines how high the image’s resolution is.

Resolutions: In printing, DPI (dots per inch) refers to the output resolution of a printer, and PPI (pixels per inch) refers to the input resolution of a photograph or image represented on a screen. DPI refers to the physical dot density of an image when it is reproduced as a real physical entity, for example printed onto paper. A digitally stored image has no inherent physical dimensions, measured in inches or centimetres.

DPI is used for printing and PPI for digital.

Export for Web and Digital Publishing: Most screens have 72 pixels per inch (or 96ppi) so if you want your viewer to preview your images at the best resolution (without weighting down your server with unnecessary data), then you should export your images at 72ppi. On the other hand, at 72ppi, your viewer won't be able to zoom on your image, so if you want to give them the option to zoom (200%), you will need to double the resolution, so in that case you should export your files at 144ppi (common for e-magazines)

Adobe Photoshop Screenshot

To change the resolution of an image on Photoshop go to Edit -> Image Size

Export for Print: Unfortunately, when we reproduce images in print for advertising, magazines, brochures and flyers etc, that resolution needs to be much higher – ideally around 300 pixels per inch. So even if the image looks beautifully sharp on screen, it doesn't mean that it will look that sharp when printed. Professional printers print at 300 dots per inch, so if you want to print at the best possible quality, you should export your image at 300 dpi. (Home printers print at 240dpi)

  • Print: 300dpi

  • Web/Digital: 72ppi (100% preview)

  • Web/Digital: 144 ppi (200% preview)

Adobe Photoshop Screenshot

If you want to check what's the largest size that you can print your image without having any pixelation or quality loss go to Edit -> Image Size and uncheck the option Resample. Then, if needed, change the resolution to 300ppi (it's very important to do every step with this order). Unchecking the Resample option means that your image's resolution won't change no matter what changes you make on this window. Instead of resampling, Photoshop will show you your image's ideal print size. Which means that now you know what's the largest size that you can print your image without losing any quality.

At the given example, I can print my image at 16.93cm x 11.3 cm (or smaller) without having any quality loss.

On the other side, if you need to print your image larger than the given number, you shouldn't have any visible quality loss if you enlarge your image no more than 20%. If you enlarge your image more than 20% you risk losing sharpness and quality.

Please feel free to ask me any questions at the comment section.

Sofia Katsikadi

Adobe Certified Instructor - Adobe Certified Expert - Adobe Education Trainer

#adobe #photoshop #digital #media #resolution #bitmap #raster #adobe #resize #resample #dpi #ppi #image #photo #size

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© Sofia Katsikadi All Rights Reserved
Edinburgh, Scotland, United Kingdom