JPEG, GIF… or else? Part 1: Basics

Yes, we all work with images from time to time: sales or marketing, managers or programmers – we draw, we send, we copy and paste…

But do we always understand what type of image to use, if we have a choice and why? So here are some tips to help you:

Rules of thumb

I will talk only about most widely used types – or formats – of images: those with file extensions of GIF, JPEG (or JPG) and PNG. And of course, if you are a professional graphics designer, you would know more than this blog can tell you.

So for a start, here are my “rules of thumb”:

  • GIF format is for logos, diagrams, and simple images like thisLogo image as a GIF file
  • Example of a photoFor photos and images with many details like this  – use the JPEG format.
  • If you’re not sure, use PNG and
  • have a good habit of forgetting that there is such format as BMP.

Why you need to know this?

There are two aspects you really care about:

  1. Image quality, and
  2. The size.

When you have  images somewhere on your computer, you cannot make it look better, but you can make it smaller – and uglier too.

So when you should you care about changing the image format? When you publish it for others to see: via email, on a blog site, and so on – for yourself, you probably just keep the best original you get, in whatever format.

Once you decide to publish your image in some form, this is the time to consider saving it in a different format.

Let us look at what difference it can make to image size and quality.

A simple logo

The original PNG version Sample PNG logo image is 1.72 KB in size

The same file saved as GIF takes 1.73 KB

Logo image as a JPEG file at 100% qualityBut in JPEG format – which requires you to select the quality or the compression level – it takes 5.89 KB at 100% quality:

and 1.83 KB at 50% quality:
Logo image as a JPEG file at 50% quality
 

But look at how distorted it becomes!


So we return to the “rules of thumb” – and now we see why JPEG is not to be used for such logos.

A photograph

The original PNG version is huge 47 KB: Photo in PNG format


Saved as GIF, the file takes only 11.8 KB:


In JPEG, the 100% quality image takes 20.9 KB


and at 50% quality, only 3.84  KB:


Both GIF image:


and low quality JPEG image:


distorted the photograph, each in it its own way – but I think JPEG version still is more realistic, and much smaller. Once again, JPEG is the format for photos.

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