Shadow and highlight enhancement refers to an image processing technique used to correct exposure.
The use of this technique is has been gaining popularity,[ citation needed ] making its way onto magazine covers, digital media, and photos. It is, however, considered by some[ by whom? ] to be akin to other destructive[ citation needed ] Photoshop filters, such as the Watercolor filter, or the Mosaic filter.
A conservative application of the shadow/highlight tool can be very useful in recovering shadows, though it tends to leave a telltale halo around the boundary between highlight and shadow if used incorrectly. A way to avoid this is to use the bracketing technique, although this usually requires a tripod.
Recovering highlights with this tool, however, has mixed results, especially when using it on images with skin in them, and often makes people look like they have been "sprayed with fake tan".
One way to brighten shadows in image editing software such as GIMP or Adobe Photoshop is to duplicate the background layer, invert the copy and set the blend modes of that top layer to "Soft Light". You can also use an inverted black and white copy of the image as a mask on a brightening layer, such as Curves or Levels.
Several automatic computer image processing-based shadow recovery and dynamic range compression methods can yield a similar effect. Some of these methods include the retinex method and homomorphic range compression. The retinex method is based on work from 1963 by Edwin Land, the founder of Polaroid. [1]
Shadow enhancement can also be accomplished using adaptive image processing algorithms such as adaptive histogram equalization or contrast limiting adaptive histogram equalization (CLAHE).
Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll. Since then, the software has become the industry standard not only in raster graphics editing, but in digital art as a whole. The software's name has thus become a generic trademark, leading to its usage as a verb although Adobe discourages such use. Photoshop can edit and compose raster images in multiple layers and supports masks, alpha compositing and several color models including RGB, CMYK, CIELAB, spot color, and duotone. Photoshop uses its own PSD and PSB file formats to support these features. In addition to raster graphics, Photoshop has limited abilities to edit or render text and vector graphics, as well as 3D graphics and video. Its feature set can be expanded by plug-ins; programs developed and distributed independently of Photoshop that run inside it and offer new or enhanced features.
Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as sound, images, and scientific measurements. Signal processing techniques can be used to improve transmission, storage efficiency and subjective quality and to also emphasize or detect components of interest in a measured signal.
Halftone is the reprographic technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect. "Halftone" can also be used to refer specifically to the image that is produced by this process.
In art, craft, and engineering, masking is the use of materials to protect areas from change, or to focus change on other areas. This can describe either the techniques and materials used to control the development of a work of art by protecting a desired area from change; or a phenomenon that causes a sensation to be concealed from conscious attention.
Unsharp masking (USM) is an image sharpening technique, often available in digital image processing software. Its name derives from the fact that the technique uses a blurred, or "unsharp", negative image to create a mask of the original image. The unsharp mask is then combined with the original positive image, creating an image that is less blurry than the original. The resulting image, although clearer, may be a less accurate representation of the image's subject. In the context of signal processing, an unsharp mask is generally a linear or nonlinear filter that amplifies the high-frequency components of a signal.
Tone mapping is a technique used in image processing and computer graphics to map one set of colors to another to approximate the appearance of high-dynamic-range images in a medium that has a more limited dynamic range. Print-outs, CRT or LCD monitors, and projectors all have a limited dynamic range that is inadequate to reproduce the full range of light intensities present in natural scenes. Tone mapping addresses the problem of strong contrast reduction from the scene radiance to the displayable range while preserving the image details and color appearance important to appreciate the original scene content.
An image histogram is a type of histogram that acts as a graphical representation of the tonal distribution in a digital image. It plots the number of pixels for each tonal value. By looking at the histogram for a specific image a viewer will be able to judge the entire tonal distribution at a glance.
Image file formats are standardized means of organizing and storing digital images. An image file format may store data in an uncompressed format, a compressed format, or a vector format. Image files are composed of digital data in one of these formats so that the data can be rasterized for use on a computer display or printer. Rasterization converts the image data into a grid of pixels. Each pixel has a number of bits to designate its color. Rasterizing an image file for a specific device takes into account the number of bits per pixel that the device is designed to handle.
Kai's Power Tools are a set of API plugins created by Kai Krause in 1992 that were designed for use with Adobe Photoshop and Corel Photo-Paint. Kai's Power Tools were sold to Corel when MetaCreations was closed.
Histogram equalization is a method in image processing of contrast adjustment using the image's histogram. Histogram equalization is one of the best methods for image enhancement. It provides better quality of images without loss of any information.
In digital photography, exposing to the right (ETTR) is the technique of adjusting the exposure of an image as high as possible at base ISO to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor.
Helicon Filter, also referred to as Helicon, Filter, or as HF, was a proprietary commercial and shareware photo editing software program for Microsoft Windows, similar to such programs as Adobe Photoshop and GIMP, developed and published by Helicon Soft Ltd. Unlike these other programs, Helicon Filter is designed primarily to edit and improve existing photos and not for graphics creation. Helicon Filter's interface also differs from other programs in that compact toolbars and menus containing editing tools are replaced with labeled "filter" tabs, each tab containing labeled edit options specific to a single aspect of the picture. Although some editors used to Photoshop-style programs may initially find this layout unfamiliar and unlike the standard toolbar layout, beginners and those who don't recognize the standard icons generally find this very helpful for getting through the editing process.
De-essing is any technique intended to reduce or eliminate the excessive prominence of sibilant consonants, such as the sounds normally represented in English by "s", "z", "ch", "j" and "sh", in recordings of the human voice. Sibilance lies in frequencies anywhere between 2–10 kHz, depending on the individual voice.
Adaptive histogram equalization (AHE) is a computer image processing technique used to improve contrast in images. It differs from ordinary histogram equalization in the respect that the adaptive method computes several histograms, each corresponding to a distinct section of the image, and uses them to redistribute the lightness values of the image. It is therefore suitable for improving the local contrast and enhancing the definitions of edges in each region of an image.
SilverFast is the name of a family of software for image scanning and processing, including photos, documents and slides, developed by LaserSoft Imaging.
Image editing encompasses the processes of altering images, whether they are digital photographs, traditional photo-chemical photographs, or illustrations. Traditional analog image editing is known as photo retouching, using tools such as an airbrush to modify photographs or editing illustrations with any traditional art medium. Graphic software programs, which can be broadly grouped into vector graphics editors, raster graphics editors, and 3D modelers, are the primary tools with which a user may manipulate, enhance, and transform images. Many image editing programs are also used to render or create computer art from scratch.
CVIPtools is an Open Source image processing software. It is free for use with Windows, and previous versions are available for UNIX. It is an interactive program for image processing and computer vision.
Aurora HDR is photographic software developed by Macphun Software for Mac OS X and Windows. MacPhun changed its name to Skylum in early 2018.
EasyHDR is a High Dynamic Range (HDR) image processing software that merges differently exposed photographs into HDR radiance map and tone maps them. With a single photograph, easyHDR can be used to increase contrast and refresh colors.
JPEG XT is an image compression standard which specifies backward-compatible extensions of the base JPEG standard.
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