Page 169 - DCAP303_MULTIMEDIA_SYSTEMS

Unit 10: 3D Modelling and Animation Tools

modified more easily, because they contain descriptions of the shapes for easy rearrangement. notes
They are also scalable, being rasterizable at any resolution.
10.2.2 automatic image enhancement
Camera or computer image editing programs often offer basic automatic image enhancement
features that correct colour hue and brightness imbalances as well as other image editing features,
such as red eye removal, sharpness adjustments, zoom features and automatic cropping. These
are called automatic because generally they happen without user interaction or are offered with
one click of a button or mouse button or by selecting an option from a menu. Additionally,
some automatic editing features offer a combination of editing actions with little or no user
interaction.
Traditional analogue image editing is known as photo retouching, using tools
such as an airbrush to modify photographs, or editing illustrations with any
traditional art medium.

10.2.3 Digital Data Compression
Many image file formats use data compression to reduce file size and save storage space. Digital
compression of images may take place in the camera, or can be done in the computer with the
image editor. When images are stored in JPEG format, compression has already taken place. Both
cameras and computer programs allow the user to set the level of compression.
Some compression algorithms, such as those used in PNG file format, are lossless, which means no
information is lost when the file is saved. By contrast, the JPEG file format uses a lossy compression
algorithm by which the greater the compression, the more information is lost, ultimately reducing
image quality or detail that cannot be restored. The JPEG uses knowledge of the way the human
brain and eyes perceive colour to make this loss of detail less noticeable.
10.2.4 image editor features
Listed below are some of the most used capabilities of the better graphic manipulation programs.
The list is by no means all inclusive. There are a myriad of choices associated with the application
of most of these features.
selection
One of the prerequisites for many of the applications mentioned below is a method of selecting
part(s) of an image, thus applying a change selectively without affecting the entire picture. Most
graphics programs have several means of accomplishing this, such as a marquee tool, lasso tool,
magic wand tool, vector-based pen tools as well as more advanced facilities such as edge detection,
masking, alpha compositing, and colour and channel-based extraction.

Layers
Another feature common to many graphics applications is that of Layers, which are analogous
to sheets of transparent acetate (each containing separate elements that make up a combined
picture), stacked on top of each other, each capable of being individually positioned, altered and
blended with the layers below, without affecting any of the elements on the other layers. This is
a fundamental workflow which has become the norm for the majority of programs on the market
today, and enables maximum flexibility for the user while maintaining non-destructive editing
principles and ease of use.

image size alteration
Image editors can resize images in a process often called image scaling, making them larger, or
smaller. High image resolution cameras can produce large images which are often reduced in size

LoveLy professionaL University 163