Thursday, September 2, 2010

What Are JPEG, GIF, PNG File Formats And How Are They Different From Each Other?

What is JPEG?

JPEG or JPG (often pronounced as jey-peg) is an image format used to save images in a compressed format and to make them lightweight so that they can be used in websites. Today JPEG is the most common image format used to transfer the data over web and mobile as well as digital camera devices. It supports 16.7 million colors which is highly greater than GIF which supports only 256 colors.

JPEG is an abbreviation of the Joint Photographic Experts Group. It is the committee that wrote and developed the standard, hence the format is named after them. JPEG is basically developed to compress the real world images like photographs which contains thousands and millions of colors. However for computer generated images like vectors arts and cartoons it is found to be non-effective as usually it doesn't contain millions of color shades. GIF format is generally used to compress such images.

JPEG format compresses the image without losing the quality of an image. To compress the image it removes the unwanted pixels and color information in an image which is not recognized by human eye. The human eye can not perceive the minute details of the picture and JPEG eliminates that unwanted pixel information to compress the image. Thus the output we get with JPEG is a highly compressed image with better picture quality visible to human eye. However the errors left by jpeg can be identified if the compressed image is analysed by a machine analyser which has far better perception than the human eye.

What is meant by 'Progressive' JPEG?

While saving the jpeg as progressive gives an illusion of gradually loading graphic. It means when a web page is being loaded, a jpeg image appears to be blur at first and when a page is completely loaded, an image also loads completely. It helps to give an illusion of progressive loading to user and make him stay on a web page.

What is GIF?

GIF stands for Graphic Interchange Format. It is the most commonly used graphic format for the compression of images which include vector lines, illustrations and text. This format is used to compress the images which are usually machine generated or vectors or line drawing and illustrations like logos, icons, etc. Unlike JPEG, it supports only 256 colors and hence it is not considered ideal for raster photographs taken by digital camera devices. However it compresses the data and gives a very quality output within this limitation. If you want to reduce the file size further, you can simply reduce the number of colors from 256 to 126 and below at the compromise of quality.

GIF Supports Transparency

GIF format supports transparency in image. Hence when an image with transparent background is needed, GIF is used. However it doesn't support transparency with faded gradient. For this purpose, PNG format is preferred.

What is Interlacing?

Interlacing gives an illusion of gradual loading image. When a web page loads, an image appears blur as if the data is being loaded and when the page loads completely an image is also loaded fully. Though while publishing GIF with interlaced option gives heavy file size. Hence it should be used only according to the requirement.

Animation with GIF images

One more best feature of GIF is that it supports animation. Small animations can be created in GIF using software like GIF animator, Adobe Photoshop, Adobe Fireworks etc. GIF animation are quite popular since they are lightweight and take less time and skill to produce.

What is PNG?

PNG stands for Portable Network Graphics. PNG is comparatively newer file format and is developed to replace the GIF format. While GIF format supports either fully opaque or transparent effect, PNG – with its 8-bit transparency channel - supports the gradient effect from full color to transparent gradients. So with its support to gradients and transparency it is widely supported by almost all browsers out there. However as it can not make small animations like GIF.

How to Compress an Image to reduce the File Size?

you can compress an image (be it jpeg, gif or png) using anny standard image editor like Adobe Photoshop. However if you want to edit it further, there are plenty of online image compression tools available. Try using or for better results. These tools help removeing extra metadata information associated with the images thereby reducing the file size further.

Final Words

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