User manual

Functional Descriptions 387

JPEG (*.jpg)

Advantage:

The Joint Photographic Experts Group Format (JPEG) format allows for control on the

compression quality. This means that you can opt for a smaller image with less detail or a larger

image with more detail. JPEG handles gradients well and is useful for images with subtle color

borders such as photographs.

Disadvantage:

JPEG files are typically large files, and the JPEG formatted images lose quality rapidly as they

are compressed, usually introducing ‘noise’ and distortion into the image. The loss of image

quality is usually not worth the reduction of file size.

JTIF (*.jpg)

JTIF ( JPEG File Interchange Format) is just a file format for a compressed JPEG image. TIFF

can actually store its pels compressed in a wider variety of ways, including JPEG. JTIF is the

common JPEG file format seen in *.jpg files.

RAW (*.RAW)

RAW is a file format used in Vision Research applications for storing an interpolated image as an

array of bytes. For each pixel, three values are written to the file in ASCII or Binary format,

depending on the user option.

Usually, a RAW file contains just the array of bytes without any additional information.

Nevertheless, both image size and color depth can optionally be included in the file header.

Because of its simplicity, RAW files are rather suitable for in house post processing applications

where acquisition parameters are well known and controlled values.

This format is a Vision Research proprietary format that contains only pixel values. The file exists

for developers of custom software.

DNG (*.dng)

DNG (Digital Negative) is a non-proprietary file format developed by Adobe Systems and used for

storing RAW images. DNG is TIFF/EP standard compatible.

A DNG file contains unprocessed, uninterpolated data. Additional information about acquisition

and processing parameters is stored separately in the file as metadata.

One great advantage of the DNG file format is its flexibility: the end-user has access to the

original sensor data and can modify a wide range of parameters such as color interpolation, white

balance, black level, contrast, saturation, etc.

On the other hand, each DNG needs to be processed before being used, which not only that is

time consuming, but also requires specialized software tools for handling DNG files.