File Formats: JPEG and LEAD Compressed (JPG, J2K, JPX, JP2, CMP, and CMW)

LEADTOOLS reads and writes the following LEAD and JPEG compressed formats:

• LEAD. This is the LEAD CMP compressed format for grayscale and color images. This format results in smaller files and better image quality than industry-standard formats. In addition, LEAD also supports CMW files, which use Wavelet CMP compression in 8, 12, and 16-bit grayscale and 24-bit color. Support for writing CMW files is included with Imaging Pro, Document and Medical Imaging toolkits.

• Progressive LEAD. This is a LEAD format that is useful for transmitting images, because the first part of the file contains the full dimensions of the image. Therefore, in a paint-while-load routine, you can display the whole image, then progressively clarify it as the rest of the file loads. In this format you can read and write 8 or 24 bits per pixel, where 8 is for grayscale and 24 is for color.

• Lossy JFIF. This is the JPEG File Interchange Format. LEADTOOLS supports YUV 4:4:4, 4:2:2, and 4:1:1 color spacing, and YUV 4:0:0 for grayscale.

• Lossless JFIF. This is the JPEG File Interchange Format. LEADTOOLS supports 8, 12, and 16-bit grayscale and 24-bit color spacing. Please note that not all applications support Lossless JPEG. Before saving a file using Lossless JPEG, make sure your reader supports it.

Both JPEG 4:4:4 and Lossless JPEG will be recognized when getting file information.

12 and 16-bit grayscale images are only supported in the Document and Medical Imaging toolkits.

NOTE: JFIF  4:1:1 and 4:2:2 formats use subsampling for the color components. In the case of 411, the color components for 4 pixels is averaged during compression. This will cause a color shift, but the shift is tolerable for low compression ratios. If you have high compression and repeated savings, then the color shift will increase.  Due to inherent limitations of the JPEG algorithm, the only ways to avoid this are: (a) avoid repeated load and resave, or (b) use 4:4:4  format, which has no subsampling.

• Progressive JPEG. This is a JFIF format that is useful for transmitting images, because the first part of the file contains the full dimensions of the image. Therefore, in a paint-while-load routine, you can display the whole image, then progressively clarify it as the rest of the file loads. LEADTOOLS supports YUV 4:4:4, 4:2:2, and 4:1:1 color spacing, and YUV 4:0:0 for grayscale.

• Lossy JTIF. This is the JPEG Tagged Interchange Format. LEADTOOLS supports YUV 4:4:4, 4:2:2, and 4:1:1 color spacing, and YUV 4:0:0 for grayscale.

• Lossless JTIF. This is the JPEG Tagged Interchange Format. LEADTOOLS supports 8, 12, and 16-bit grayscale and 24-bit color spacing. Please note that not all applications support Lossless JPEG. Before saving a file using Lossless JPEG, make sure your reader supports it.

Both TIFF JPEG 4:4:4 and Lossless JPEG will be recognized when getting file information.

12 and 16-bit grayscale images are only supported in the Documentand Medical Imaging toolkits.

• J2K - Lossy or Lossless. This is a JPEG 2000 format. LEADTOOLS can read  8, 12, and 16-bit grayscale and 24, 32, 48 and 64--bit color images. The J2K format contains only a stream of image data. All LEADTOOLS SDKs read J2K files. J2K write (save) support is included with toolkits.

• JP2 - Lossy or Lossless. This is a JPEG 2000 format. LEADTOOLS can read  8, 12, and 16-bit grayscale and 24, 32, 48 and 64-bit color images. The JP2 format contains a stream of image data, plus extra data about the organization and contents of the file. All LEADTOOLS SDKs read JP2 files. JP2 write (save) support is included with toolkits.

• JPX (JPEG 2000 Part 2) - This JPEG 2000 format is especially useful for document, medical, and satellite imagery archiving systems.  All LEADTOOLS SDKs read/parse JPX files. JPX write/update (save) support is included with toolkits.

• TIF J2K - Lossy or Lossless. This is a Tagged Image File with JPEG 2000 Compression. This file format contains only a stream of image data. LEADTOOLS supports reading  8, 12, and 16-bit grayscale 24, 32, 48 and 64-bit color spacing. All LEADTOOLS SDKs read J2K files. J2K write (save) support is included with toolkits.

For general information, refer to Compression Using LEAD and JPEG Formats. For instructions for implementing progressive formats, refer to Controlling Progressive Loads and Saves. JPEG and LEAD files can contain many comment fields of various types. You can use the L_ReadFileComment function to read comments in an existing file. Before writing a file, you can use the L_SetComment function to create an array of comments to be saved in the file.

Please note that the LTCLR DLL is required for loading JPEG CMYK images and for loading and saving JPEG LAB images.

File constants associated with this file format are:

Required DLL: For a listing of the exact DLLs needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Related Formats: EXIF - Exif Formats, FPX - Kodak Format, TIFF - Tagged Image File Format.

Platforms

Windows 2000 / XP/Vista, Windows CE.

See Also:

Compression Using LEAD and JPEG Formats

JPEG and LEAD Compressed Formats

Introduction: Bitmaps in Memory and in Files

Programming with JPEG 2000 Features

Raster Image Functions: Working with JPEG 2000

JPEG and LEAD File Comments

JPEG 2000 File Comments