Computer Programming: Image Editing
Computer programming in the context of image editing involves utilizing software to manipulate digital images in various ways. This can include enhancing image quality, altering visuals to create imaginative effects, and compressing files for more efficient storage and transmission. The process typically starts with obtaining a digital image, which can be done through photography, scanning prints, or creating images directly on digital tablets. Once an image is digitized, users can choose to enhance its quality through mathematical adjustments or apply filters to correct issues like noise.
Image editing encompasses both destructive and nondestructive methods; the former permanently alters the original file, while the latter saves changes separately, preserving the initial image. Compression techniques are crucial in this domain, especially for reducing file sizes, often at the cost of some image quality. The algorithms used for compression can significantly decrease file sizes—by up to 90%—without noticeable quality loss for most applications. Mobile platforms have further expanded the accessibility of image editing, with various applications available for both desktop and mobile devices, enabling users to edit images conveniently across different formats and settings.
Computer Programming: Image Editing
FIELDS OF STUDY
Digital Media; Graphic Design; Software Engineering
ABSTRACT
Image editing software uses computing technology to change digital images. Image editing can involve altering the appearance of an image, such as showing a hot air balloon underwater, or improving the quality of a low-resolution image. Images may also be compressed so that they require less computer storage space.
Overview of Image Editing
There are as many ways of digitally altering images as there are uses for digital art. The first step in image editing is to obtain an image in digital format. The easiest method is to use a digital camera to take a photograph and then transfer the photograph to a computer for editing. Another approach that is occasionally necessary is to scan a print photograph or film negative. This converts the photo to a digital image ready for editing. It is even possible to create an image by hand in native digital format, by using a tablet and stylus to draw and paint. Finally, rendering makes it possible for a computer to produce a digital image from a 2-D or 3-D model.
Once the digital image is available, the next step is to determine what will be done to it. Most often, the image will be enhanced (improving the image quality through interpolation or other techniques), compressed (decreasing the file size by sacrificing some image quality or clarity), or altered (made to depict something that was not originally there). These changes may be through destructive or nondestructive editing. In destructive editing, the changes are applied to the original file. By contrast, in nondestructive editing, they are saved in a separate version file.
In the early days of the Internet, image compression was an especially important type of image editing. Bandwidth was limited then, and it could take several minutes to transmit even a medium sized image file. Image compression algorithms were invented to help reduce the size of these files, with some loss of quality. Lossless compression can avoid degradation of the image, but in most cases, it does not reduce file size as much as lossy compression does.
How Compression Works
Computers store image data as sets of numeric values. Each pixel onscreen is lit in a particular way when an image is displayed, and the colors of each pixel are stored as numbers. For example, if the color black were represented by the number eight, then anywhere in a picture that has three black pixels in a row would be stored as 8, 8, 8. Because an image is composed of thousands of pixels, all of the numbers needed to describe the colors of those pixels, when combined, take up a lot of storage space. One way to store the same information in less space is to create substitutions for recurring groups of numbers. The symbol q1 could be used to represent three black pixels in a row, for instance. Thus, instead of having to store three copies of the value "8" to represent each of the three black pixels, the computer could simply store the two-letter symbol q1, thus saving one-third of the storage space that otherwise would be required. This is the basis for how digital images are compressed.
Most images are compressed using lossy compression algorithms, such as JPEG. Compression thus usually requires that the sacrifice of some image quality. For most purposes, the reduction in quality is not noticeable and is made up for by the convenience of more easily storing and transmitting the smaller file. It is not uncommon for compression algorithms to reduce the file size of an image by 75 to 90 percent, without noticeably affecting the image's quality.
A Numbers Game
Image enhancement typically relies on the mathematical adjustment of the numeric values that represent pixel hues. For instance, if an image editor were to desaturate a photograph, the software would first recognize all of the pixel values and compare them to a grayscale value. It would then interpolate new values for the pixels using a linear operation. Similarly, a filtering algorithm would find and apply a weighted average of the pixel values around a given pixel value in order to identify the new color codes for each pixel being adjusted. The median or the mode (most common) value could also be used. The type of filter being applied determines which mathematical operation is performed. Filters are often used to correct for noise, or unwanted signal or interference.
Image Editing Goes Mobile
Image editing is now even possible on mobile platforms. Certain programs work only on PCs, others strictly on mobile devices, and still others on both. Besides the well-known Adobe Photoshop, other programs, including iPhoto, Apple Photos, Google's Picasa, and Gimp, also provide image editing for desktop computers. Fotor and Pixlr Editor work across platforms, giving users flexibility between their desktop, mobile device, and the Web. Similarly, photo collaging software abounds. Among these programs are Photoshop CC and CollageIt on desktops, Ribbet and Fotojet online, and Pic Stitch and BeFunky on mobile devices.
Nokia and Apple have developed the capability to create "live photos" with their smartphones. These are a hybrid of video and still images in which a few seconds of video are recorded prior to the still photo being taken. This feature represents yet another direction for image capture, alteration, and presentation.
Bibliography
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Freeman, Michael. Digital Image Editing & Special Effects: Quickly Master the Key Techniques of Photoshop & Lightroom. New York: Focal, 2013. Print.
Galer, Mark, and Philip Andrews. Photoshop CC Essential Skills: A Guide to Creative Image Editing. New York: Focal, 2014. Print.
Goelker, Klaus. Gimp 2.8 for Photographers: Image Editing with Open Source Software. Santa Barbara: Rocky Nook, 2013. Print.
Holleley, Douglas. Photo-Editing and Presentation: A Guide to Image Editing and Presentation for Photographers and Visual Artists. Rochester: Clarellen, 2009. Print.
Xue, Su. Data-Driven Image Editing for Perceptual Effectiveness. New Haven: Yale U, 2013. Print.