Different Types of Computer Game Graphics

There are six different kinds of graphics used in video games today. These are Background Art, Texture Art, Pixel Art, Interface, Print Media, and Concept Art. Each of these will be explained in detail below;

Background Art
This is used to encompass the game and fill up the background with appropriate designs. Examples of the kind of images used include skies, mountains, etc., anything that one would see around them to make the game look more professional add an element of realism, and give a sense of perspective. Background art also includes things like structures and buildings. This can help set the scene and let the players know where they are.  

The quality of background art differs from artwork used in foreground in that it's usually higher quality, depending on the style or theme of the game. It allows there to be differentiation and allows the player to focus on the actual gameplay. Background art can be done in many different styles, including traditional styles such as painting or through digital media such as Photoshop.

Sources: http://www.incredibleart.org/jobs/video.html, http://en.wikipedia.org/wiki/Background_artist


Above is an example of background art used in Halo: Reach, obtained from http://halo.wikia.com/wiki/File:Boneyard_Panorama.jpg  It shows an expansive, desolate wasteland used for shipbreaking.

Texture Art
This is art that is applied to models in a game such as objects, characters, and the immediate environment. Deep, rich textures allow a game to look more lifelike and professional. It is created digitally using software such as Photoshop or Maya. Texture art includes things like dents and scratches on metal, and fine details in things like sand or rock, it is subtle details that go unnoticed in real life but are essential to making a game look as professional or lifelike as possible.
Nowadays improved technology has allowed more extensive and realistic texture art and this has helped video game graphics to become more and more detailed.


Above is an example of Crysis 3's impressive and lifelike textures, image from http://i2.minus.com/iIVSy3mmxtTJx.jpg

Pixel Art
This is a method of creating art by using digital software to create a raster image. This image is then edited pixel by pixel. This is primarily used in 2D videogames, and was extremely popular years ago before 3D games became the standard. There are two different ways to create pixel art; isometric which refers to using 30 degree angles, and non-isometric which means only using front, top and side perspectives.

To create pixel art, a Line Drawing must be made first, either by hand and scanned in or on the computer itself. It is then coloured pixel by pixel, and since pixel art has a limited pallet a technique known as dithering is used to create different colours. This involves using two different colours of pixel in one area, where they seem to blend and create another colour. In Pixel Art it is vital that the image does not lose quality, so it is saved in .gif and .png formats to avoid this and keep file sizes low.

Source http://iconlibrary.iconshock.com/design/pixel-art-definition-examples-and-explanation/


Above is an example of pixel art from Pokémon from http://indesignartandcraft.com/wp-content/uploads/2012/10/pixel-art-pokemon.png .

Interface Art This is artwork used for the user interface of the game, which gives players information and allows players to immerse themselves in the world. Artwork used in the interface serves the sole purpose of giving players relevant information. Good interface artwork is minimalistic and too the point, clearly conveying the appropriate information. It includes in game menus, and HUD's (Heads Up Display). An in game menu such as the pause menu, will show details such as Save, Load, Options, Exit and a HUD will show a target reticule, ammo counters, motion trackers; things which show the players status and immerses them in the world.
http://gamedev.tutsplus.com/tutorials/aesthetics/game-ui-by-example-a-crash-course-in-the-good-and-bad/

The HUD from Halo 3 is an example of a User Interface

Image from http://images2.wikia.nocookie.net/__cb20100705132552/halo/images/7/76/H3_MkVI_HUD.jpg

Print Media
This is anything that presents information in a printed manner, the most common examples being things like posters, and video game cover art, newsletters and game manuals. In video game cover art, the images shown often surpass the limitations of the game to make it look better but feature screen shots of the game on the back. Programs like Photoshop and Illustrator. Print media is used to promote the game and introduce viewers to it, giving people a rough idea of what the game entails. It is important that artwork used in print media catches peoples attention and gives an insight to the themes and styles used in the game.

Info from http://www.ehow.com/about_7221638_definition-print-media_.html http://dictionary.reference.com/browse/print+media


Above is the cover art for Halo 3: ODST from http://www.covergalaxy.com/forum/attachments/microsoft-xbox-360/6971d1253996522-halo-3-odst-cover-ntsc-halo-3-odst.jpg

Concept Art
Before a video game is made, concept art has to be made to visualise the ideas for characters, objects and environments in the game. It is a form of illustration made solely to convey initial ideas or themes for film, comics, and video games. The concept artists job is to create artwork for something that does not yet exist, and interpret ideas to come up with creative, appropriate designs that can be worked on over time to come up with the most suitable design. Concept art is generally done in pencil as sketches initially, and concept artists may draw many different interpretations of an idea resulting in a lot of concept art for one character or object. It is also done in full colour using traditional and digital techniques.
Source http://en.wikipedia.org/wiki/Concept_art
Concept art from Halo: Combat Evolved from https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjM1W5vbLYF38j-YtMkjNX7yY2bZfocF_GhVYxIuyaoAEjFwyB_cFmX5xX7gqX3We7P3xzXOIGsTWy-bYyQiI-BdcSjKCfFarFZ_QB5QDwTr7RIQ0K6xAcYu-MzTKSm84MLMbnN8qF_m0k/s1600/Halo2_Concept_3.jpg
Coloured concept art of a character, from
http://printf.eu/wp-content/uploads/2012/04/dragon-s-dogma-concept-art.jpg

File Extensions

When creating images for games, there are many different file types that can be used. Each one is used for a different purpose and it is important to know the background and uses of each type.

PSD Files
These are propriety files used specifically with Adobe Photoshop. Photoshop saves files as this by default, and once opened again the image is in the same condition in Photoshop as it was before, including all layers and effects. This allows it to be ready to edit. The only drawback to this is they have very large file sizes.  Photoshop gives the option to compress these files and save them as non-propriety formats such as JPG, GIF, TIFF, etc. however they cannot be reverted back.
Source  http://whatis.techtarget.com/fileformat/PSD-Adobe-Photoshop-default

JPEG Files
A JPEG is a compressed image file format with no limit on the colours that can be used like a GIF file has. This has lead it to being the most common type of image file used around the internet. JPEG stands for Joint Photographic Experts Group, after the committee that created the file type. Although JPEGs can create colourful, high quality images, they are lossy file types, meaning they lose quality every time the image is compressed. This may not be noticeable until the file has been compressed a lot of times, then it can end up looking blocky and low quality.
Source http://pc.net/glossary/definition/jpeg
Below is an image that shows what happens as the file is compressed more;

http://www.exposureguide.com/images/file-formats/jpeg-compression.jpg

BMP Files
BMP is short for Bitmap. It is a raster image file type that originated on the Windows operating system. Colour is stored for each pixel without compression, meaning although high quality images can be produced, file sizes are often very large. File types such as JPEG are also Bitmaps, but they use compression algorithms to decrease their file sizes. This means that files such as those are used on the internet, while the BMP file type is used for images that are to be printed.
Source http://www.techterms.com/definition/bmp

PNG Files
PNG stands for Portable Network Graphic, and it was developed by the PNG Development Group and released in 1996. It was designed to be a patent free alternative to the GIF format and is expected to replace it as it improve on many of the GIF formats features, such as better compression and smaller file sizes. It is a raster format, and it is lossless meaning it does not lose quality when compressed and decompressed. It supports pallet based images, grayscale images, and full colour non-palette images however as it was designed for online image sharing rather than professional use; it does not support non-RGB color spaces.
Source http://en.wikipedia.org/wiki/Portable_Network_Graphics
The image below shows comparison between a JPEG and a PNG

http://upload.wikimedia.org/wikipedia/commons/a/a4/Comparison_of_JPEG_and_PNG.png

TIFF Files
TIFF stands for Tagged Image File Format. It is a Raster/Bitmap file type and produces high quality images. It was created in 1986 by Aldus Corporation with the intention of it being the sole file type used by companies for black and white scanned images. It was later given a color pallet and nowadays is used by graphic artists for high color depth images. It is supported by almost all image manipulation software. TIFF files make use of a lossless data compression technique called LZW compression.
http://whatis.techtarget.com/fileformat/TIF-Tag-image-bitmap-file-TIFF

GIF Files
A GIF, or Graphic Interchange File format, is a compressed image format. The compression formula it uses was created by CompuServe. They are based on index colours, meaning a GIF can support a colour pallet of 256 colors. This results in a small file size, meaning they are often used across the Internet as they can be sent easily. They make great icons and animations but since they have a limited colour palette, they are unable to be used for large, high quality images.
http://www.techterms.com/definition/gif

http://www.practicalecommerce.com/files/images/0001/0138/file_type_comparison.png

 

Image Capture

Scanner

A scanner is a device that creates digital versions of photographs or written work by scanning them and converting it into a digital file. This file can then be viewed and edited on the computer like other image files, and it would typically be saved as a JPEG file. Scanners are usually flatbed devices, meaning they have a flat scanning surface that makes it easier to scan things such as books or magazines. When a scanner is bought, it will come with software that needs to be installed first before it can work. This software imports data from the scanner and allows the user to initiate and configure scans. The scanning process consists of several stages. Firstly, the document is placed on the glass plate and the cover closed. The cover is usually white, and provides a uniform background colour that the scanner can use as a reference to determine the documents size. Next, the document is illuminated by a lamp which may be cold cathode fluorescent lamp, or a xenon lamp. Scanning can then proceed, and the scan head (Which consists of mirrors, the lens, the filter and the CCD Array) moves slowly along the document until it achieves a pass; a single total scan of the document. A curved mirror (Curved to focus the image) then reflects the image onto another curved mirror, and then onto the lens. The lens then focuses the image through a filter on the CCD Array.

Older scanners worked using a three pass technique. This is where the Scan Head needs to make 3 complete scans of the document, one for each colour filter; Red, Green and Blue. Once the scans are complete the 3 images are assembled into 1 fully coloured image. Nowadays scanners often use a 1 pass technique where the Lens splits the image into 3 smaller versions, and these are put through a colour filter. The image is then combined into a full-colour version. The parts that make up a scanner are; the Charged Coupled Device (CCD) Array, Mirrors, the Scan Head, the Lens, Filters, a Glass Plate, Lamp, and Cover, the Stepper Motor, Stabilizer bar, a belt, and finally the power supply, interface ports and control circuitry. The most important feature is the CCD array, which is the part that allows for image capture. It consists of many Light Sensitive Diodes, called Photosites. The final aspect is image transfer, which is commonly done by USB connection as it is efficient and affordable, however methods like Small Computer System Interface or FireWire are used too. Also, driver software needs to be installed that can communicate with the scanner. Scanners know the language TWAIN, and the TWAIN driver acts as an interpreter between the computer and the scanner.

http://www.techterms.com/definition/scanner
http://computer.howstuffworks.com/scanner2.htm

Digital Camera

The digital camera is a device that can take photographs and store them digitally so they can be transferred on to a computer and be viewed or edited there. Digital cameras feature built in computers and capture images electronically. When a digital camera takes a photo, it samples the light coming from an object, and breaks the light down into a series of pixel values. It is recorded in a digital form that consists of a long string of binary code, and these represent the information in each of the pixels in the photo. The camera breaks light into electrical charges by using sensors, this censor is usually a CCD or Charged Coupled Device. This is, put simply, like an array of millions of tiny solar cells that convert light into electrons. When a camera takes a photo, the detail is determined by the amount of pixels used for the photo; it's Resolution. Mote pixels mean a better quality images. On a good camera, resolutions of at least 1600 x 1200 would be used, with top of the range cameras using as high as 4064 x 2704.

On a digital camera, the one way to capture colour is to use three sensors each with a different colour filter; red, green or blue. A Beam Splitter is used to split the light equally between the filters, each of which sees the same image but only in the colour of the filter. They are then combined to create a full colour image. The best way however is to use a colour filter array placed over each photosite. The colour filter array breaks a sensor up into red, green and blue pixels and enables it to make a very accurate guess about the true colour of an object according to other pixels near the sensor. This process is called Interpolation, and allows for smaller, cheaper cameras. Demosaicing Algorithms are used to convert this mosaic into a full colour version, on the basis that each coloured pixel can be used over and over. Colours for one pixel are found by getting an average of values from surrounding pixels. Once a photo is taken, it can be viewed immediately on the LCD screen, but it can also be sent to a computer via USB or other methods. Typically this means the photo must be converted to a file format suitable for storing and transferring to a PC. Common file types used are TIFF, and JPEG as they create high quality images (Although TIFF files have a large file size).
http://electronics.howstuffworks.com/cameras-photography/digital/digital-camera1.htm

Lossy and Lossless Compression

An image file type can either be lossy or lossless. This determines the kind of quality the image will be when it is saved or edited.

Lossless Compression

Lossless compression means that when a file is compressed, it will not lose any quality. It allows for large, high quality images to be saved and compressed, and have a smaller file size but retain their quality. Examples of file types that use this kind of compression are GIFS and PNG, which are commonly used across the internet for their ability to be shared easier than other image file types and still be good quality. The technique used to compress images in lossless compression essentially rewrites the information contained in the file more efficiently, and although the resulting file is smaller, it is not as small as a file produced by lossy compression. This type of file type is good for things such as concept art and graphic design where images or often manipulated.
http://searchcio-midmarket.techtarget.com/definition/lossless-and-lossy-compression

Lossy Compression

Lossy compression works by erasing redundant information in an image file and therefore permanently reducing the file size. This results in a smaller file than if lossless compression were used however there is much more of a decline in quality (Although it is not noticeable when the image has only been saved or edited once or twice). This is especially noticeable when the image has been saved many times, as the image will lose more quality each time it is saved making it look "blockier" and more "pixelated" every time. However file types such as JPEGs have a Quality Settings feature where, upon saving the image, one can chose how much they want the image to be compressed. For example, a highly compressed image would take up very little disk space but may not look as good as the original. This is useful for sharing images online.
http://www.techterms.com/definition/lossy

To compare the two; lossy compression offers smaller file sizes that take up less disk space and are easy to send over the internet however the image quality is very low. Lossless compression allows for very high quality images due to it's advanced compression technique, however it produces larger file sizes than lossy compression would meaning more disk space is taken up.

The picture below shows the different between a PNG file which uses Lossless compression, and a JPEG using Lossy compression;

http://images.sixrevisions.com/2010/11/17-02_lossy_lossless.jpg

Vector & Raster Images

A digital image can either be a Raster or Vector image. There are many differences between these two types and each one has it's own purpose, advantages and disadvantages.

Raster Graphics

These types of graphics are made up of a grid of many pixels (A bitmap), and are the most common kind of graphics seen on a computer. For example, images imported from a camera or found the internet are raster images. Typically the larger and higher quality the image is, the more pixels it will contain and the larger the size of the file will be as information has to be stored for more pixels. For example a image of size 100x100 will contain significantly less pixels than an image of size 1800x2100, and the latter will take up a lot more disk space. To deal with the issue of larger file sizes, various raster file types with different compression algorithms were developed that compress the image and reduce the file size. Formats such as JPEG and GIF are good examples of this. The downside to raster graphics is that they cannot be resized or altered without losing quality, for example if a JPEG image is resized to be made larger, it will look 'blocky' or 'pixelated' and look very low quality. For this reason, raster graphics are not as useful for images such as logos which need to be resized often.
http://www.techterms.com/definition/rastergraphic

Below is in example that shows what happens when part of a raster image is enlarged;


http://vector-conversions.com/images/raster_vs_vector_1.jpg

Vector Graphics

Unlike Raster Graphics that are made up of thousands of pixels, vector images are composed of lines, curves and shapes defined by mathematical expressions. They are made up of Vectors or Paths, which are drawn through Control Points. These points have an absolute position on the x and y axis of the image and contain information on it's location and the direction the vector is meant to take. A colour, shape and fill can also be assigned to each vector. The main advantage of using a Vector file is that it can be resized to any size at all without loss of quality. This is because it is not made up of a set amount of pixels, instead a vector file describes how the image is to be drawn out by paths or vectors. This is useful for businesses who need to resize images such as logos. A vector image can be created and edited in programs such as Adobe Photoshop, Adobe Illustrator and Inkscape and file types associated with it include SVG (Scalable Vector Graphics), EPS (Encapsulated Post Script), and DRW (Drawing).
http://www.techterms.com/definition/vectorgraphic
http://en.wikipedia.org/wiki/Vector_image_format

Below shows what happens when a vector image is resized in comparison to a resized raster graphic. (Although the image itself is not a vector as they cannot be placed in this document)

http://en.wikipedia.org/wiki/File:VectorBitmapExample.svg