Raster equals pixels, vector equals lines. But if there are just these two kinds of image types, why do we have so many different graphics file formats? File extensions are confusing. Today we shall break down when, where and why each of these extensions are used.

Types of file formats-

1.      Raster Based

a.      JPEG or JPG

Joint Photographic Experts Group (JPEG) is a standard format meant for both web and print use. It does not support a transparent background. Jpegs are commonly used for lossy or irreversible compressions. The resolution and quality can be varied depending whether it is used for desktop printing, web viewing or emailing. CMYK, RGB, and Grayscale are the colour profiles jpegs support. Each pixel in a coloured Jpegs can store up to 24 bits per pixel, which makes jpegs capable of supporting over 16 million colours. Alpha channels are not supported by them.

When to use:

·        Post photos and images online.

·        Web-viewing or e-mailing to clients.

·        For printing at high-resolution.

When not to use:

·        When separate layers are needed for edits. Jpegs are flat images flattened to a single

layer.

·        When a graphic is needed with transparency.

b.      GIF

Graphics Interchange Format (GIF) is used for web and mailing uses. It has an alpha channel that supports transparent backgrounds and is a lossless type graphic. It is majorly used for web animated graphics like banners, buttons, memes and email animations. Gifs can store up to a maximum of 256 distinct colours and therefore shall not be used for high-resolution photographs.

When to use:

·        To generate web animations.

·        Graphics with flat colours without gradients.

·        Small files

When not to use:

·        When high-quality images with more colour variations is needed.

c.      PNG

Portable Network Graphics (PNG) is a high-quality bitmap type image file with lossless data compression. It supports an alpha channel which when applied to the three standard colour formats (RGB) gives 256 different levels of transparency. PNGs can store up to 24 bit per pixels like JPEGs and hence can produce over 16 million colours.

When to use:

·        Transparent graphics which are lossless.

·        Website and digital uploads where SVG is not supported.

When not to use:

·        When dealing with artwork or photographs that need to be printed.

d.      TIFF

Tagged Image File Format (TIFF) is a large high-quality format commonly used for desktop publishing and photography in professional environments. They support CMYK, RGB, Lab, Indexed Colour, Grayscale, and Bitmap colour modes. Professional cameras generally store images in a TIFF format.

When to use:

·        For work where high-quality scans are needed to showcase all details clearly.

·        For printing high-quality work.

When not to use:

·        When you want to publish images on the web, TIFF comes as a heavy file and hence uploads become too slow. At times, many browsers do not support TIFF images.

e.      PSD

Photoshop Document (PSD) is an image format in which an image has multiple separate layers which are fully editable. The most interesting part about a PSD is that it can be saved into all major file formats.

When to use:

·        For editable content like website design, photo retouch, editable artwork and graphics.

·        Create small animations and video clips with effects and filters.

When not to use:

·        PSDs are not universal and require Adobe Photoshop to be opened. Hence, these are not an appropriate method for exchange.

·        Many printers don’t print from PSDs.

2.      Vector Based

a.      AI

Adobe Illustrator has AI as its proprietary vector image format. Apart from vector graphics, raster or embedded graphics may also be linked into the AI file. This file format is typically the master file where all the edits can be made without losing on quality. Since Adobe Illustrator is a prerequisite to view this type of files, the AI file is typically exported as EPS or SVG.

When to use:

·        When editable vector graphics are needed.

·        For logos, branding or icons.

When not to use:

·        When imported raster graphics need to be edited.

b.      SVG

Scalable Vector Graphics (SVG) uses an XML format for describing two-dimensional graphics. SVG supports 24-bit colours hence high-resolution dynamic images can be generated. It can be modified using XML tools. It is a lossless and editable file which also supports transparency.

When to use:

·        Logos, icons and graphics for web publishing.

When not to use:

·        SVG are line and point based files and cannot display details like a similar pixel-based file.

c.      EPS

Encapsulated Postscript (EPS) is mostly used for vector graphics, but can also be used for raster graphics. It is largely supported by major graphic and page layout programs. Being a vector-based format, it is scalable to any size and is therefore used for both small and large formats of the same design.

When to use:

·        For showing logos, templates and pamphlets to clients. You need not worry if they will be seeing it in a print version, or a monitor or a projector. It won’t pixelate.

When not to use:

·        Web-publishing as many browsers don’t support EPS uploads.

d.      PDF

Portable Document Format (PDF) is an image format that draws its name from its function, that is, being portable. It is used to display documents and graphics as finalised, as is hence nearly universal. It can contain both vector and raster graphics, and can be editable or non-editable depending on how it is generated.

When to use:

·        To print, PDF is the savviest option.

·        When exchanging files on a web medium, PDFs are an easy option where the data is not lost and delivered in the same size as created.

When not to use:

·        When you want multimedia like animations or videos.

Use this guide to make sure the next time you save or send your files, the file format is not an issue.