In this report I will be discussing file formats and applications software that are the most commonly used in today’s media industry. Experience and creative skills are essential in being able to produce effective print products and graphics using image design software that is always developing and evolving. This report will include discussion of file formats used by Adobe programmes.
Graphics can be used using Vector or Bitmap processes.
Bitmap graphics are ideal for digital printing as they have the ability to produce photo-realistic and detailed images, and weilding the “paintbrush” tool, you can see what you’re creating in real-time which is a strong advantage. They can also produce simplistic images.
Most Bitmaps can also be read by most bitmap-based software. Certain file formats such as PNG or JPEG can be written and read by every paint programme.
Vector images can be used for a variety of digital graphics. Line art such as charts and graphs are the most common.
Vector images are created using lines and simple shapes and the art is resolution-independant. This means that there are no dots being used to create the image and quality isn’t sacrificed when enlarging an image.
Vector images are produced using mathematical equations and algorithms.
Adobe Photoshop is a bitmap programme.
An advantage of PhotoShop it its layers feature. The layers are similar to layers of acetate stacked one on top of another. You’re able to see through transparent areas of a layer to view the layers below.
As mentioned in the introduction, PhotoShop is a bitmap programme and thus is able to create fantasy or creative images. It can also be used to manipulate or “correct” photos.
Unfortunately, bitmap image files, particularly on PhotoShop, can be very large due to information being stored in every pixel. Image enlargement can be restricted by the original size of which the image was created. The quality will decrease if a file is produced as a size larger than the resolution will allow. Pixilation can occur if an image is printed in a low resolution.
In programmes like Photoshop, “dithering”, also known as “colour quantization” is a technique that can be performed to create the illusion of colour depth. This technique is used for images that have a limited colour palette.
Colours that aren’t available in
the palette are approximated by a diffusion of coloured pixels extracted from the colour palette that is available.
Selecting the “Save For Web” option on Photoshop also allows for an image to be optimised and compressed without losing quality.
PhotoShop can also be used for “antialiasing”. This is a software technique that is used to diminish “jaggies” or stair-like lines that should be smooth.
Jaggies are a result of an output device such as a printer or moniter not having a high enough resolution to produce a smooth image.
An alternative to antialiasing is “smoothing”. The printer changes the horizontal alignment and size of the dots to make smoother curves.
Unfortunately these techniques, as shown in the above image, can also make the jagged appearance of lines appear fuzzier.
Adobe Illustrator is a vector programme which makes it perfect for designing logos and cartoons, but can take a long time to create photo-realistic images. Illustrator uses mathematical algorithms to create and draw shapes and stores information on a grid of dots. This keeps the file sizes small as it doesn’t need to store too much information. Vector graphics are scalable without the sacrifice of quality or resolution.
Adobe Illustrator has a file extension called “AI”.
Adobe Illustrator also has a file extension called EPS (Encapsulated PostScript). An EPS file can contain graphics and text and usually contains a bitmap version of an image as this allows for simpler viewing.
Adobe InDesign is a vector programme used purely for layouts, not manipulating images. Its intended use is multi-page documents such as books or magazines and it has a “book feature” and multiple layers feature so that workloads can be split and each page of the product can have individual attention. The latest versions of InDesign have been heavily focused on digital publishing for devices such as eBooks or PDFs.
Adobe InDesign is a stronger programme than Adobe Illustrator in two respects. The first being that Illustrator doesn’t have the necessary tool to build documents that use templates and doesn’t have a way to set up master pages to resolve this.
Secondly, InDesign supports the automatic numbering of pages which is a useful feature when working with large documents.
Compression – Lossy and Lossless
Compression can be lossy or lossless.
Lossless compression means a file size is compressed but the quality of the picture remains the same and does not decrease. The file can also be decompressed to its original quality.
Lossy compression permanently removes and deletes data.
JPEG is a commonly used lossy compression method for digital images for digital photography. Allowing a reasonable negotiation between image quality and storage size, you can adjust the degree of compression. A disadvantage of compressing a JPEG file, however, is that every time it is compressed, the quality is degraded.
Digital cameras and other devices that capture images use JPEG as a standard image format. JPEG is also the most common form for transmitting and storing images on the internet.
TIFF (Tagged Image File Format) is a computer file format used for storing raster graphics images. It’s popular amongst photographers, the publishing industry and graphics artists. Image-manipulation applications, page-layout applications and publishing applications are widely supported by the TIFF format.
Unlike JPEG files, TIFF files don’t use compression because it’s not universally supported.
PNG (Portable Network Graphics) is another raster graphics file format and it supports lossless data compression. It’s a non-patented and improved replacement for the GIF (Graphics Interchange Format) file format and on the internet it’s the most used lossless image compression format.
Palette-based images (palettes of 24-bit PGB or 32-bit RGBA colours, a full-colour non-palette based RGB images and grayscale images are all supported by PNG as PNG was not designed for professional-quality print graphics, but rather for the transferring of images on the internet.
GIF (Graphics Interchange Format) is a bitmap image format. Due to its portability and wide support it has come into widespread usage on the internet.
The GIF format supports 8 bits per pixel per images and thus allows a palette of up to 256 colours from the 24-bit PGB colour space to be references but a single image. The same palette of 256 colours is also supported for each frame of an animation.
These palettes can have their limitations, however, so the GIF format can be less suitable for producing colour photographs. It is, however, well-sited for graphics, logos or simpler images with solid areas of colour.
Lossless data compression is used to compress GIFs and this allows for a reduction of the file size but no reduction in quality.
PDF (Portable Document Format) is a file format that presents documents in a way that is separate and independent of hardware, operating systems and applications. PDF files envelop a full description of a fixed-layout flat document including graphics, fonts, text and other information essential for displaying it. Incorporating text, however, can be difficult as PDF software interprets the text as pictures. Similarly is isn’t easy to edit PDF files as specialist programmes are needed. It also isn’t free to edit PDF files.