Choosing the Right Image Format

Whenever it come to images, they often share things in common–a tool of visual information. From my findings, despite so many image formats out there, the most common we found are utilizing JPEG, GIF, or PNG format and in some cases, BMP to say the least.

Choosing the appropriate web-based format for your images is the first step towards optimized web graphics. As you get clearer, let us discuss the most widely used formats–the JPEG, GIF, and PNG, and when to use them.

JPEG (JOINT PHOTOGRAPHIC EXPERTS GROUP)
This format is an alternative to GIF developed specifically for photographic images. JPEG supports millions of colors (24-bit). JPEG is a lossy format, which means that some image data is lost when the image is compressed, reducing the quality of the image. JPEGs can also be saved as Progressive JPEGs, which reduces the size of the image. The JPEG format is best for scanned photographs or images that require more than 256 colors.

GIF (GRAPHICS INTERCHANGE FORMAT)
GIF is a bitmap format developed for CompuServe by a company that is now part of UNISYS. GIF is a variable 8-bit format that compresses bitmap files into half of their original size, and supports transparency. GIF is a lossless format, which means that no image quality is lost when the image is compressed. The GIF format is best for button, background image, simple image that uses 256 colors or less.

PNG (PORTABLE NETWORK GRAPHICS)
This is another widely used format that is in fact, the most versatile of the current web graphic formats. However, only newer web browsers can take full advantage of PNG characteristics such as 32-bit color and transparency. PNG compression is a lossless format and can compress more than a GIF or JPEG of the same color depth and quality, resulting in smaller file size. The PNG format is best suited for creating high-color graphics or better compressed low-color graphics.

For samples, WebSite Optimization has created some of them.

As you get the picture, which format should you use? There’s just not a good answer to this question. No matter what I say, someone else can give you just as compelling a reason why you should do the opposite.

In general, as a standard practice, save your photographic images as JPEGs and save your graphical images (using 256 colors or less) as GIFs, if they are to be used for the web. Save your images as PNGs only if you are confident that your users are using newer browsers that support the format.

By now, you should realize how important it is in choosing the right format of your image. Don’t forget to optimize it further as described in the previous post. Just remember, there are no right or wrong answers when using image format. Pretty much anything goes.

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Posted on: June 16, 2008 | Under Blog Optimization 
 

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