session 19

a)Find out the most common formats for images and write a shortdescription of the features of each of them

Let us tackle the five most common image formats for the web and computer graphics: JPEG, GIF, BMP, TIFF and PNG.

                                                JPEG

JPEG is short for Joint Photographic Experts Group, and is the most popular among the image formats used on the web. 

Pros of JPEG:

• 24-bit color, with up to 16 million colors
• Rich colors, great for photographs that need fine attention to color detail
• Most used and most widely accepted image format
• Compatible in most OS (Mac, PC, Linux)

Cons of JPEG:

• They tend to discard a lot of data
• After compression, JPEG tends to create artifacts
• Cannot be animated
• Does not support transparency

                                                     GIF

GIF, short for Graphics Interchange Format, is limited to the 8 bit palette with only 256 colors. GIF is still a popular image format on the internet because image size is relatively small compared to other image compression types.

Pros of GIF:

• Can support transparency
• Can do small animation effects
• ‘Lossless’ quality–they contain the same amount of quality as the original, except of course it now only has 256 colors
• Great for images with limited colors, or with flat regions of color

Cons of GIF:

• Only supports 256 colors
• It’s the oldest format in the web, having existed since 1989. It hasn’t been updated since, and sometimes, the file size is larger than PNG.

                                                    BMP

The Windows Bitmap or BMP files are image files within the Microsoft Windows operating system. In fact, it was at one point one of the few image formats.

These files are large and uncompressed, but the images are rich in color, high in quality, simple and compatible in all Windows OS and programs. BMP files are also called raster or paint images.

Pros of BMP:

• Works well with most Windows programs and OS, you can use it as a Windows wallpaper

Cons of BMP:

• Does not scale or compress well
• Again, very huge image files making it not web friendly
• No real advantage over other image formats

                                                          TIFF

TIFF was created by Aldus for ‘desktop publishing’, and by 2009 it was transferred to the control of Adobe Systems.  It is also popular among Apple users.

Pros of TIFF:

• Very flexible format, it supports several types of compression like JPEG, LZW, ZIP or no compression at all.
• High quality image format, all color and data information are stored
• TIFF format can now be saved with layers

Cons of TIFF:

• Very large file size–long transfer time, huge disk space consumption, and slow loading time.

                                                           PNG

PNG or (Portable Network Graphics) is a recently introduced format, so not everyone is familiar with it. But PNG has been approved as a standard since 1996. It is an image format specifically designed for the web. PNG is, in all aspects, the superior version of the GIF.

Just like the GIF format, the PNG is saved with 256 colors maximum but it saves the color information more efficiently. It also supports an 8 bit transparency. 

Pros of PNG:

• Lossless, so it does not lose quality and detail after image compression
• In a lot ways better then GIF. To start, PNG often creates smaller file sizes than GIF
• Supports transparency better than GIF

Cons of PNG:

• Not good for large images because they tend to generate a very large file, sometimes creating larger files than JPEG.
• Unlike GIF however, it cannot be animated.
• Not all web browsers can support PNG.

b) Which image format preserves the quality better when it is compressed? tiff preserves the best quality when it is compressed
c) Which formats are more suitable for web design? jpej and gif are the more suitable formats