This post is about image file formats for artists and bloggers. I'm writing it to remind myself of the basic characteristics of different formats because I'm in the middle of getting to grips with a new graphics program. This means I'm revisiting a lot of the basics as well as learning new stuff. It's reminding me of how much there is to learn when you start to use images on the internet.
Which file formats should I use for what - and why?
Very basic simple images for the internet
What you want: something very simple in colour terms and quite possibly very small eg an avatar
- use a GIF file (Graphics Interchange Format) which is limited to an 8-bit palette, or 256 colors making it very suitable for very simple graphics files
- It can render the image exactly and keep the file size small so long as the colour is one of the 256 colours.
What you want: images which look good on screen and load quickly. They don't need to be big or to be capable of being printed.
- always use a compression format (eg jpeg or gif) if you want an image to load quickly
- a typical jpeg file is still too big for the internet so needs to be made web-ready
- create a web-ready jpeg through compression to (say) no more than a 100KB file - this means that they look good on the internet; are useless when printed out (ie protects copyright concerns) and they load quickly and do not deter people from visiting your website or blog
- reduce the size of the image (ie reduce the pixel dimensions) to create a web-ready file. I typically make the longest side no more than 500 pixels and very rarely use anything over 1,000 pixels on the internet
- reduce the number of dots per inch (dpi) to make a smaller file. This is different from reducing the dimensions. 72 dots per inch (dpi) is a good standard for web-ready jpeg files. (It's the one I always use) A lower dpi can lead to more pixelated images. A bigger dpi can create large files which take longer to load
what you want: images which look excellent and comply in every way with the technical requirements of formats for entry
- always comply with whatever the requirements are for type of file format and maximum size in terms of pixels and kilobytes
- create a file which is the maximum allowed as this creates the best chance of creating an impressive image
- if you can submit via a disc or via an upload to a formal submission website use an uncompressed file format (eg TIFF) if possible. This will create very large files of as good a quality as possible (but it won't make a bad photo look good - quite the reverse!)
- if you have to submit online using email consider using jpeg - but appreciate that the quality of file may be less good than those submitted by others
- find out how jurors will review the images. If they are reviewing via a slideshow or on a monitor screen then they certainly don't need to be 300 dpi (the standard for good quality prints)
- always make sure you know how to create a new format/upload to a submission before you run out of time!
what you want: the very best quality image with the potential to print to the largest size possible
- File format assumes you want the very best result possible - which means no compression or loss of pixels
- unless you have an A3 scanner of good quality, large work needs to be photographed to a professional standard and you need to save the digital photos in the correct image file format
- Use an uncompressed file format (eg TIFF - which can be created from jpeg files). This will: enable you to produce files with high quality images and create exceptionally large files
- enable you to achieve the maximum possible size of image for the given image
TIP: if you ever want to check out what the file format of your image actually looks like then use the 'view actual size' option in the 'view' option. This shows you thse size and quality of the image you've created.