File Types

Now I am well underway with making both my DVD inlay and my disk overlay I have taken sometime to look into the different file types I could use when I come to the stage of exporting and saving. File types are really important when we consider the quality and size of an image. It is often the larger file sizes which create the highest quality images and the lower the file size the poorer the overall quality. This was something which I have known and stuck too throughout my years at A-Level and so far with my degree however as part of a lecture we spent sometime looking at this in more detail. Before I go into what I did and the results of this I will look at the file types on offer.

To begin with I looked into the different file types I could save a Bitmap image too. There are five main options. The most obvious and simple file type from Photoshop is a PSD. This is simply the Photoshop file. This is fine in most cases but not compatible with the web and hence we use one of the other four options. BMP. This stands for Bitmap. The most common way these are used is to save a PSD file for use on the web. The next notable file type is JPG. This is abbreviated from JPEG. Photographs are often saved in this form. This is based on the fact that it used Lossy Compression. This is something I will look at in more detail later in the post. The next Bitmap file type is GIF. This is an abbreviation of Graphic Interchange Format. This format is a common file type used on the Web. It, unlike JPG uses Lossless Compression. The final notable bitmap file type is PNG. This stands for Portable Network Graphic. This has over the years replaced GIF and is hence a Lossless compression format. It is said to be an improved version of GIF and is for that reason the most commonly used file type for the internet.

All Bitmap images use compression techniques when saving in various file types. There are two main compression techniques, these were briefly touched up above and are Lossy and Lossless. The main principle behind Lossy compression is the idea of discarding some of the image. Lossy compression discards pixels which are not a key feature of the image. This reduces the file size but if taken too far the quality. On a small scale it is very hard to tell that an image has been compressed using Lossy and hence most of the time we wouldn't even know that the file type has done this however over do it and the image quality can be noticeably damaged. Lossy compression is often used in Media streaming and for the use of images on the internet. The issue with Lossy compression is that when the image has been compressed it is no longer possible to regain all the compressed pixels.This is something of the opposite to Lossless compression. This is a compression technique where by you can regain the compressed material. Lossless compression simply compresses what is already there. Nothing is lost. This is why it is most commonly used for text files and Zipzs. These would be damaged completely if they were compressed using Lossy. The file size of Lossless compressed material is still considerably reduced just in a non-destructive way.

All of the above are aspects which must be considered when exporting my final images for display. Getting this wrong could severely damage the quality of my image and final product. As mentioned though these aspects only relate to Bitmap images. This is a key feature of my Photoshop designs however my illustrator designs wont be effected by this quite so much.

Illustrator is a piece of Vector Software. This means that it uses vector shapes as opposed to Bitmap. Vector images are not made up of pixels and hence can be blown up to large sizes without damaging the quality of the image. This makes life a little easier! There are 3 main Vector file types. Like with Photoshop, Illustrator has its own file type. this is known as AI and stands for Adobe Illustrator. Again like Photoshop this file type can not be used on the Web and hence we need to look for alternatives. The two main vector file types in addition to AI are PDF and SVG.

PDF is a very common file type throughout many different environments. It stands for Portable Document Format. A PDF file encapsulates the original file and hence doesn't damage it in anyway. PDF documents are not in my opinion the best way to display images online. They work much better with larger file types in terms of text. The second and least common vector file type is SVG. This is an abbreviation for Scalable Vector Graphics. This immediately sounds better in terms of this in particular project. This is a two dimensional vector image format which is used massively among the World Wide Web. SVG files can be compressed if they are needed using Lossless Compression however this isn't a standard feature. This seems by far the better exporting options for me in terms of exporting vector shapes and images as whole, even though they are not intended for the Web.

Within the lecture on this topic I undertook some testing. This testing allowed me to change various aspects of each image in different file types. I was then able to compare their sizes and the give each image a mark out of 10 for their quality. I worked on two different images. The first image was a photograph of a set of cables and the second image was a the UCP logo. One Bitmap and one vector. The Tables below show the file size and my rating for each.

 

 

As you can see from my tests above there were very few images with a variation in quality when changing the various settings. This suggests to me that when it comes to deciding my file formats it will be a case of what works best for my images rather than having to use a specific file format.

Overall this research has given me invaluable knowledge of the different file types and the background/basics of each. It has made me think about what the file type I chose can do the final product I produce and how I need to chose a file type which will preserve my image to the best of its ability. I have also learnt the differences between Bitmap and Vector file types and how these two different image types actually create two very different issues.