File Formats Research Part 1

Overview:

As a publisher or publishing company, people must deal with a range of different file formats and learn what is preferred to be used for different things such as graphics creation, final design exporting, photograph editing and also moving image file types. It is also important to learn different file types and what to use for publishing on the web and the size, colour as well as difference between pixel and vector images.

. PNG - PNG stands for Portable Network Graphics and is a raster graphics file format which supports the ability of lossless data compression. The .PNG file was created to be an improved replacement for the .GIF file format but non-patented. Since then, a .PNG has become the most used lossless image compression format to be used on the internet.

What uses does a .PNG have and why use a .PNG?

A .PNG is most commonly used on the web because of its lossless data compression, images are more clearer and have more colours than a .GIF file can hold which means you see more of what the image is actually like. One downside to a .PNG is that the file size can vary greatly depending on a number of different factors, these are those factors:

• Colour Depth - This can range from 1-60 bits per single pixel
• Ancillary Chunks - A PNG supports metadata which is useful for editing but not needed for viewing on websites.
• Interlacing - When each pass of the Adam7 algorithm is separately filters, the file size can increase considerably
• Filter - Filter is a pre-compression stage in creating and saving a .PNG, each line is filtered by a predictive filter which is different from line to line. You are unable to optimise this row by row however though, therefore the choice of filter for each row is then potentially very variable.

. TIFF - A .TIFF file stands for a Tag Image File Format and is similar to a .PNG in the sense that it is a raster graphics file format and is commonly used for exchanging these images between application programs such as Adobe Photoshop. .TIFF files are also used for when you scan an image into your computer which can also be later worked on in image editing or publication programs.

What uses does a .TIFF have and why use a .TIFF?

.TIFF files are used and can be used in several different publishing techniques, these include desktop publishing, faxing, 3D applications and also medical imaging applications. A .TIFF is used when all detail of the image must be preserved and the file size doesn't matter or isn't taken into consideration which is why most professional and commercial printing needs are done with this file format. They also support a number of different classes too, which includes the following:

• Grayscale - Greyscale is the range of different shades, from white to black which are used in a monochrome display or printout.
• Colour Palette - Logical colour numbers are stored into each pixel, normally represented as RGB ( Red, Blue and Green)

. JPG - Joint Photographic Experts Group

A .JPG is a file extension commonly used for lossy compression and is used mainly for digital photography. The file format allows you to change quality via the compression rate, decreasing or increasing it dependant on its resolution. To further explain what i mean by this, here is a photograph of a cat and as the compression rate increases and decreases.

As you can clearly see, the quality over the whole image improves a lot the less you compress and more you leave its quality high. This does come with a problem though, the higher quality your .JPG looks, the bigger the file size will be compared to whether you compress it down. Though you can compress the file as low as shown on the left of the image, this is rarely done because of its pixelation and how bad the quality becomes.

What uses does a .JPG have and why use a .JPG?

The .JPG is the most common file format for storing and transmitting photographs across the World Wide Web. Because of this, these images are used in websites to display and provoke more thought to a piece of text. A .JPG is used because of its lossy compression, meaning its compression and quality can utterly depend on your preference and can also maintain a small file size if needed.

. TGA - A TGA (TARGA) file stands for Truevision Advanced Raster Graphics Adapter. Like the previously mentioned .PNG and .TIFF, it is also a raster graphics file format. Resolutions of .TARGA image files usually match those of NTSC and PAL video formats and was created for video editing with PCs by Truevision Inc. 

What uses does a .TARGA have and why use a .TARGA?

A .TGA is most commonly used for video tape and video publication, specifically they are used in the rendering of still images and to render sequences of still image to video tape. You should use a targa file if you're creating anything to be used and added into video such as image stills and multiple images to create a sequence of moving image. Another reason they're used is because the format can store image data with different bits of precision per pixel. These are the following bits a TGA allows:

• 8 bits
• 15 bits
• 16 bits
• 24 bits
• 32 bits