Image codec

Codec

• Codec is a device or computer program for encoding or decoding a digital data stream or signal.
• A codec encodes a data stream or a signal for transmission and storage, possibly in encrypted form.
• The decoder function reverses the encoding for playback or editing
• Codecs are used in video conferencing, streaming media, and video editing applications.

Image codec

• Image codec is a method of compression or decompression of image files or image data.
• These image codec are depends on various algorithms.
• They have different specification and application in various fields.

Types of image codec

BMP

• Windows Bitmap format codec,provides full Microsoft BMP support for all known variants (except Header Version 5.x) as well as the older OS/2 variant.

Advantages

• Good photo quality.
• BMP may be easily created from existing pixel data stored in an array in memory.
• Bitmap codecs may translate well to dot-format output devices such as CRTs and printers.

Disadvantages

• Bmp codecs are Limited to RGB-images.
• These codecs generally does not support effective image compression.
• They can be very large, particularly if the image contains a large number of colors.
• It’s also not supported well across multiple platforms.
• Shrinking this image change the image in an unacceptable manner.

JPEG

• Joint photographic expert group file format codec, support 24 GB RGB and grey scale.

Advantages

• JPEG codec has low complexity, picture quality is generally good enough.
• This is also memory efficient i.e good compression allows to reduce the file size.
• It works very well for “slide-show” movies that have a very low frame rate.

Disadvantages

• Single Resolution & Single Quality.
• No target bit rate.
• Blocking artifacts at low bit rate.
• No lossless capability.
• No tailing No regions of interest.

TIFF

• Tagged image file format saves eight bits or sixteen bits per color (red, green, blue) for 24-bit and 48-bit totals.

Advantages

• Compared to a JPEG, an uncompressed TIFF codec retains the best quality of a photographic image.
• Low or high-resolution images codec of photographic quality.
• Encoding scheme is Lossless, files can be compressed or uncompressed.

Disadvantages

• Codecs produce large file size

GIF

• Graphic interchange format supports up to 8 bits per pixel for each image, allowing a single image to reference its own palette of up to 256 different colors chosen from the 24-bit RGB color space.

Advantages

• This codecs allow to create transparent, interlaced, and animated graphics for the Web.
• Compresses by scanning horizontally across a row of pixels and finding solid areas of color.
• It is universally supported by all graphical browsers, regardless of version.

Disadvantages

• This codec is not good for photographic images due to its limited number of colors generally 256 colors.

PNG

• Portable network graphics is a raster graphics file format that support lossless data compression.

Advantages

• A better compression than GIF codec, which only scans rows.
• The compression is ‘lossless’, so color information will not loss as you compress the file smaller.
• It is a best one for creating complex live transparency, high-color graphics, and better compressed low-color graphics.
• Designed to be network-friendly, so it is recognized and supported on all platforms.

Disadvantages

• It doesn’t support animation.
• It does not use predictive frames.
• It has lower quality than PICT or TIFF.