Guides: Digital Capabilities Explained: Creating and editing image files

This resource covers the basic concepts and tools you need to get started in creating and editing image files.

What should I consider before I begin?

Before creating an image, consider what your final product will be. This will help you determine what size the image needs to be as well as the resolution, colour format, and file type you need.

For example, if you need an image to fill an A4 page that you will then print, you should choose an image that is close to 210 x 290mm, 300 DPI and CMYK.

This ensures that the image won't need to be enlarged much, is going to print clearly and is the right colour format for printing.

Choosing a size

It's better to choose a larger image to ensure quality remains high.
If you try to enlarge an image that is too small to fit the space it will result in a poor quality, pixelated image.
It's best not to enlarge an image more than 125% of the original size.

Choosing a resolution

Image resolution is usually described in PPI. This stand for "pixels per inch" and refers to how many pixels are displayed per inch of an image.

Resolution can refer to how many pixels per inch an image contains, how many pixels a monitor can display or how many dots per inch a printer can print.

For images being printed

An image that is 300 PPI and used at 100% will give a good quality result.

For images being displayed online:

Monitor resolution is 72 PPI

For printers:

Printer resolution is measured in "dots per inch" (DPI). This is how fine the printer can print, the higher the DPI the better the quality is.

See the Image size and resolution page from Adobe for more information.

Choosing a colour format

Use RGB for anything appearing on a screen, such as web and video.
Use CMYK for images that will be physically printed.

Choosing an image format

Vector graphics are used in drawings, such as logos. Vector images can be scaled without quality loss.
Raster graphics are also known as bitmap images. The photos from your mobile phone are raster images. These images lose quality when resized.

Choosing an image file type

JPEG is one of the most widely used file formats. Use this format for photos/artwork on websites as they download quickly. JPEGs are good for email attachments as the file size is small. JPEGS are also suitable for printing.
PNG is an excellent format for when you need a small file; this makes it ideal for images being used on the web. They also allow transparency.
GIFs are often used for web animation as they contain the timing info and animation frames in the file. They are perfect for images to be used on websites, such as banners and icons, as the way they are compressed makes the files very small.
TIFFs are extremely high quality and an ideal file type for photography and printing. When scanning photos or documents to ensure that you have the best original file to work from.
SVGs can be scaled while retaining the quality and can be viewed on a screen of any resolution and size. Elements of the file can be animated. Used mostly for online.
EPS is the file type you would use for vector images, such as logos. With an EPS file the image will always appear at the right resolution regardless of what size you make it.
PDF stands for “Portable Document Format”. It is an ideal way to view documents in different programs or devices and it will still look the same. They are usually created form another document, such as Word.

Tools for editing images

Tool	Features	Tutorials / support	Availability
Adobe Illustrator	A vector graphics editor for creating illustrations, diagrams, line art and more.	Tutorials; Support	Paid
Adobe Photoshop	A popular tool for raster image editing, including for manipulating, creating or colour correcting images.	Tutorials Support	Paid
GIMP	A free and open-source raster graphics editor for image manipulation similar to Photoshop.	Tutorials Documentation	Downloadable via IMTS Student Software Portal
Inkscape	A free and open-source vector graphic editor similar to Illustrator.	Tutorials; Community	Downloadable via Inkscape
Pixlr X	A free browser-based photo editor.	Tutorials and support	Access online

Finding and reusing existing content

There's a lot of free content out there that you can legally remix and reuse in your own work.

Google's Find free-to-use images guide will show you how to find images you can use freely in your projects.

Other resources for finding free-to-use images

Unsplash is free to join and all photos can be used for free, no need to ask permission.
Pixabay share copyright free images and videos that can be used without asking for permission or giving credit to the artist.

For more information on finding legally free resources see our Copyright guide and the Creative Commons Frequently Asked Questions page.

Where can I learn more about image editing?

YouTube has hundreds of videos for learning how to use different image editors.

You can also try searching Google for "photo editing for beginners" or "how to edit photos like a professional" or "GIMP basics".

You will find books and ebooks in the Library SEARCH try search "photo editing".

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.