Image viewer

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IrfanView , a popular image viewer
Display of a directory of background images in Kuickshow

Image viewers are file viewers that can be used to view image files . In contrast to image management programs , they do not focus on the management of larger or very large image collections, but on the simple possibility of quick and uncomplicated viewing. It differs from image editing programs in that they often only offer rudimentary or no editing options at all.

Skills

Gwenview on KDE 4

The following skills are typically offered:

Graphic formats

An image viewer should understand the common graphic formats as much as possible . The ability to load all existing image formats is not offered by a single program, but software authors usually strive to support as many formats as possible. Last but not least, this is a popular advertising argument.

Color reduction

An image viewer must be able to display an image even if the graphics mode currently set for the user can not display all the colors that the image contains. There are various methods to show off images as well as possible even with limited color options on the output medium (image quantization and dithering ).

Scaling & rotation

Images with a resolution greater than the currently set graphics mode must be able to be scaled down by an image viewer so that they can be displayed in full. Conversely, enlargement should also be possible. A large number of levels are usually offered ( zoom ).
The program should also be able to rotate photos taken with a digital camera in portrait format and save the images in the correct position regardless of the Exif orientation. If the images have been compressed with loss (e.g. in JPEG format), they should be able to be saved without loss after rotation, i.e. H. without being recompressed.

Thumbnails

Preview images ( thumbnails ) make it possible to get a preview of the data stored in the file image to the user, completely without loading the file or the images of multiple files - simultaneously displaying an overview - about a directory. So that the preview images can be displayed more quickly, some programs save them in the file system, sometimes in a separate directory, sometimes in a special image database. It makes sense that an image viewer should be able to directly use preview images already stored in the image file itself.

Metadata display

With digital cameras and image management software becoming more widespread, the display of metadata contained in image files has also become common. This includes in particular the information stored in Exif headers and in the IPTC-IIM standard .

Additional functions

Most image viewers offer one or more additional functions:

  • Slide show shows pictures one after the other at a selectable interval without any further user action, possibly with fade effects
  • Conversion between file formats , e.g. B. from TIFF to JPEG
  • Export of image collections in a format suitable for the World Wide Web ( HTML overview page and reduced image files that can be loaded more quickly)
  • Scanning pictures
  • Simple image editing functions
  • Printing out individual images or overview pages (contact sheets)
  • Direct addressing of digital cameras

Common image viewing programs