Adobe Photoshop in the context of Adobe Systems

Layers are used in digital image editing to separate different elements of an image. A layer can be compared to a transparency on which imaging effects or images are applied and placed over or under an image. Today they are an integral feature of image editors.

In the early days of computing, memory was at a premium and the idea of using multi-layered images was considered infeasible in personal computer applications as the tradeoffs were image size and color depth. As the price of memory fell it became feasible to apply the concept of layering to raster images.The first software known to apply the concept of layers was LALF, which was released in 1989 for the NEC PC-9801. LALF's terminology for layers is "cells", after the concept of drawing animation frames over-top of a stencil. Layers were introduced in Western markets by Fauve Matisse (later Macromedia xRes),and then available in Adobe Photoshop 3.0, in 1994, which lead to wide-spread adoption. In vector image editors that support animation, layers are used to further enable manipulation along a common timeline for the animation; in SVG images, the equivalent to layers are "groups".

In photography, acutance describes a subjective perception of visual acuity that is related to the edge contrast of an image. Acutance is related to the magnitude of the gradient of brightness. Due to the nature of the human visual system, an image with higher acutance appears sharper even though an increase in acutance does not increase real resolution.

Historically, acutance was enhanced chemically during development of a negative (high acutance developers), or by optical means in printing (unsharp masking). In digital photography, onboard camera software and image postprocessing tools such as Photoshop or GIMP offer various sharpening facilities, the most widely used of which is known as "unsharp mask" because the algorithm is derived from the eponymous analog processing method.

Théâtre D'opéra Spatial (pronounced [teɑtʁ dɔpeʁa spasjal]; French for 'Space Opera Theater') is a digital arts piece generated and edited by an American man named Jason M. Allen with the generative artificial intelligence (GAI) model Midjourney. It won the 2022 Colorado State Fair's annual fine art competition in the "emerging artist" (non-professional) division of the "Digital Arts/Digitally-Manipulated Photography" category on August 29, becoming one of the first images made using GAI to win such a prize. The award came with a $300 cash prize.

Allen said he used at least 624 text prompts and revisions as inputs for Midjourney to create the initial image. He then edited it with Adobe Photoshop and upscaled it using a tool called Gigapixel AI.

Photograph manipulation or photograph alteration is the modification of an otherwise genuine photograph. Some photograph manipulations are considered to be skillful artwork, while others are considered to be unethical practices, especially when used to deceive. Motives for manipulating photographs include political propaganda, altering the appearance of a subject (both for better and for worse), entertainment and humor.

Depending on the application and intent, some photograph manipulations are considered an art form because they involve creation of unique images and in some instances, signature expressions of art by photographic artists. For example, Ansel Adams used darkroom exposure techniques to darken and lighten photographs. Other techniques include retouching using ink or paint, airbrushing, double exposure, piecing photos or negatives together in the darkroom, and scratching instant films. Software for digital image manipulation ranges from casual to professional skillsets. One of these, Adobe Photoshop, has led to the use of the term photoshop, meaning to digitally edit an image with any program.

Thomas Knoll is an American software engineer who created Adobe Photoshop. He initiated the development of image processing routines in 1988.After Knoll created the first core routines, he showed them to his brother, John Knoll, who worked at Industrial Light and Magic. John liked what he saw, suggested new features, and encouraged Tom to bundle them into a package with a graphical user interface. In 1988, John sold the distribution license for Photoshop to Adobe Systems and later on March 31, 1995, he sold the rights to the program to Adobe for $34.5 million.

Thomas Knoll was the lead developer until version CS4, and currently contributes to work on the Camera Raw plug-in to process raw images from cameras.

A Photoshop contest, or sometimes Photoshop battle (often abbreviated to PS Battle), is an online game, in which a website or user of an Internet forum will post a starting image — usually a photograph — and ask others to manipulate the image using some graphics editing software, usually Adobe Photoshop, however other editors are commonly allowed, such as Corel Photo-Paint, GIMP, PaintShop Pro, Paint.NET or even Microsoft Paint. People can also use video editing software to create these images, such as Adobe Premiere Pro, Kdenlive, OpenShot, or NCH VideoPad.

While Photoshop is the industry standard image editing program, Adobe Systems, the publisher of Photoshop, discourages use of "Photoshop" to refer to anything other than their photo editing software, to prevent their trademark from becoming generic.

Photoshop plugins (or plug-ins) are add-on programs aimed at providing additional image effects or performing tasks that are impossible or hard to fulfill using Adobe Photoshop alone. Plugins can be opened from within Photoshop and several other image editing programs (compatible with the appropriate Adobe specifications) and act like mini editors that modify the image.

Darktable (stylized as darktable) is a free and open-source photography application and raw developer. Rather than being a raster graphics editor like Adobe Photoshop or GIMP, it comprises a subset of image editing operations specifically aimed at non-destructive raw image post-production. It is primarily focused on improving a photographer's workflow by facilitating the handling of large numbers of images. It is freely available in versions tailored for most major Linux distributions, macOS, Solaris and Windows and is released under the GPL-3.0-or-later software license.