Week 8: Digital Image Management

This week we learned about image formats & how to use them.

Firstly, there are several distinctions which can be made for image formats, namely if they are bitmap or vector graphics, and what level of compression is involved.

Bitmap Image vs. Vector Graphic

A bitmap or raster image is a dot matrix data structure, which means the image is made up out of tiny pixels. This means it is not easily scalable and has a fixed size in which it is portrayed correctly and the pixels are not visible as singular objects.

A vector graphic however are made out of geometrical primitives, such as points, lines, curves and shapes. Therefore, it can be scaled to any size and still look like it is supposed to.

Uncompressed, lossless or lossy compression

Uncompressed file formats store all the original image data and are therefore quite big in file size. Lossless compression makes use of eliminating redundancy in the image to save file size while still being able to reconstruct the original completely. Lossy compression sacrifices information which is deemed irrelevant for the human eye to reduce the file size even more, this however makes the reconstruction impossible and can cause artefacts in the image.

Image formats

  • PSD (uncompressed) is the Photoshop File Format, stores all information about layers, transparency and transformations.
  • TIFF (depends) can be compressed, both lossless and lossy, popular with graphic artists and for print.
  • DNG (uncompressed) is a RAW image format with a wide colour gamut, use less file size than TIFF even uncompressed.
  • GIF (lossless compression) supports animation with a limited palette of 256 colours for each frame.
  • PNG (lossless compression) supports transparency.
  • JPG (lossy compression) is able to reduce file size significantly, but due to its nature of lossy compression can cause artifacts; still popular with sharing photographs.

Until next week!

Image Source: help.adobe.com


Week 6: Digital Imaging

This week we talked about digital image editing (cropping, retouching, resizing, etc.) and the various programs used for that.

  • Adobe Photoshop is the best known image editing software and has many powerful features. It is available on both Mac and Windows, but very expensive. Thankfully, there are many free alternatives:
  • GIMP offers most of the basic features of Photoshop but uses a very different user interface, so it may be confusing to people who are used to Photoshop. It’s an open source program and available for Mac, Windows and Linux.
  • Pixlr is an online image editing service and has an interface very similar to Photoshop. Since it is web-based, it can be used on any operating system.
  • Picasa is more of an image organizing program, but offers editing and retouching functions, too. It’s made by Google and available for both Mac and Windows. It is especially useful for batch resizing/editing images!

Until next week!

Image Sources: adobe.com, gimp.org, pixlr.com & picasa.com