Compression Using LEAD and JPEG Formats

Once you have captured an image, its file size can range from 100 kilobytes to more than 200 megabytes. Compressing color and grayscale graphic images provides the following advantages:

With LEADTOOLS Screen Capture you can control the amount of compression applied to your images, allowing image quality to match the needs of your application. The Compression Quality Factors setting allows you to specify how to handle  the trade-off between maximum quality and minimum file size.

JPEG Compliant

LEADTOOLS API is fully JPEG compliant. Any file using compression that is compliant with the JPEG Interchange File Format can be viewed and converted.

4-bit and 1-bit Images

JPEG and LEAD CMP compression are intended for use with high-resolution images. They are impractical for use with 4-bit or 1-bit images. For these images, use CCITT, LEAD 1-bit, RLE, LZW, or ZIPLib compression methods.

824-bit Images

Created by LEAD Technologies, Inc., the LEAD CMP compression format delivers a much smaller file size and better image quality than other compression techniques, including JPEG. By incorporating LEAD and JPEG image compression, files can be reduced to 200 times smaller than their original size, allowing you to develop applications that would be impractical otherwise.

Normally, to compress an 8-bit color image, internal JPEG compression functions must first convert the 8-bit data into raw RGB 24-bit format before compressing it as a color image. LEAD's CMP file format allows for decompression of a 24-bit medium at 24-bit color, or of an 8-bit medium at 8-bit color, without sacrificing image quality. This eliminates the need to save both an 8-bit file and a 24-bit file, or to convert all images to 8 bits in order to support low-end users. The result is a single file, of much smaller file size, that can be viewed on a 24-bit video card at 24-bit true color, as well as on an 8-bit VGA card at 256 colors. Thus, compressing the original 24-bit image actually results in a smaller file size and higher quality than compressing an optimized 8-bit color image.

LEADTOOLS functions compress 8-bit grayscale as 8-bit grayscale JPEG or CMP images. LEAD's CMW file format uses Wavelet CMP compression. Currently, 24-bit color images and 8, 12 and 16-bit grayscale images are supported in this format.

For more information on LEAD and JPEG compression formats, as well as other supported formats, refer to Summary of All Supported Image File Formats