Selecting LWF Encode Options

The following is a summary of the LuraWave Encode Options.

Image Quality:

Select one of the following:

  • Lossless: the resulting compression ratio depends on the image contents. Typical lossless compression ratios are 1:2, up to 1:5.

  • Lossy:some of the image quality is sacrificed to reduce the file size. The file size and quality depend on the amount the data is compressed. Select the Lossy settings.

File Types:

Select one of the following:

  • Embedded: For images that will be transmitted over the Internet, it is recommended that the embedded file type be used. The resulting file is fully embedded. The image can be displayed progressively and its quality improves during the download. An interrupt of the transmission results in a full sized image.

  • Baseline: Baseline mode does not consume as much working memory as the embedded mode. It is recommended if you are compressing very large images.

Password Protection:

Select one of the following:

Save these settings as default:

Select to save the settings for use the next time you open LuraWave. Click Reset all to reset to the system defaults.

Lossy Settings

Quality:

Set the value to a number between 1 and 100. Lower quality values give a high compression ratio but poor image quality. A high value will give poor compression but good image quality. A value of 100 will perform lossless compression. Values in the range of 50 to 100 are ideal.

Maximum File Size:

When the image must be compressed to fit a fixed file size (eg. a floppy disk) the maximum file size option can be used. The selected amount of disk space (in kilobytes) is the maximum limit for the size of the compressed image.

Compression Ratio:

Specify an exact compression ratio. The resulting file size will be equal to the size of the uncompressed data divided by the chosen rate. Images compressed with ratios up to 1:10 appear almost lossless. Photo-realistic images can be compressed to 1/20th of the original file size without any significant loss of quality. For Internet presentation, compression ratios between 1:50 up to 1:100 are recommended. Higher compression ratios up to 1:1000 can be used when image quality is not very important.

Software Key Settings

The encryption is guaranteed to work with all applications that can display LuraWaveŽ compressed images.

To enter a password:

  1. Select Use Software Key.

  2. Type a password in the Key field.

  3. Type a number in the Quality Without Key field. This number represents the percentage of the original image that is unaltered before a password is entered.

Definitions

Lossless compression: refers to data compression techniques where no data is lost (eg. PKZIP). For most types of data, lossless compression techniques will reduce the space needed by about 50%. For greater compression, a lossy compression technique should be used, but only certain types of data (graphics, audio, and video) can tolerate this compression. You must use a lossless compression technique when compressing data and programs.

Lossy compression: refers to data compression techniques where some data is lost. Lossy compression attempts to eliminate redundant or unnecessary information. Most video compression technologies (like MPEG), use this technique.