Photo and Graphic Formats - Essay Example

Contents GIF Graphics. I. JPEG Graphics. II. PNG Graphics. III. TIFF Graphics. IV. RIF Graphics. (2 BPG Graphics I. Photo-Realism II. Scalability III. Shape IV. Conversions V. File Size Table of figures i. Figure 1…………………………… Figure 2…………………………… Figure 3……………………………... Figure 4…………………………….. Figure 5……………………………… Figure 6………………………………. 1. Identify six graphic file formats: V. GIF Graphics. Graphic Interchange Format was used as an efficient means to transmit images across data networks in the 1980s. In the early 1990s the original designers of the World Wide Web adopted GIF for its efficiency and widespread familiarity. Many images on the web are in GIF format, and virtually all web browsers that support graphics can display GIF files. GIF files incorporate a lossless compression scheme to keep file sizes at a minimum without compromising quality. However, GIF files are 8-bit graphics and thus can only accommodate 256 colors VI. JPEG Graphics. The other graphic file format commonly used on the web to minimize graphics file sizes is the Joint Photographic Experts Group (JPEG) compression scheme. Unlike GIF graphics, JPEG images are full-color images that dedicate at least 24 bits of memory to each pixel, resulting in images that can incorporate 16.8 million colors. JPEG images are used extensively among photographers, artists, graphic designers, medical imaging specialists, art historians, and other groups for whom image quality and color fidelity is important. A form of JPEG file called progressive JPEG gives JPEG graphics the same gradually built display seen in interlaced gifs. Like interlaced gifs, progressive jpeg images often take longer to load onto the page than standard jpegs, but they do offer the user a quicker preview. VII. PNG Graphics. Portable Network Graphic (PNG) is an image format developed by a consortium of graphic software developers as a nonproprietary alternative to the GIF image format. PNG graphics were designed specifically for use on web pages, and they offer a range of attractive features, including a full range of color depths, support for sophisticated image transparency, better interlacing, and automatic corrections for display monitor gamma. PNG images can also hold a short text description of the image’s content, which allows Internet search engines to search for images based on these embedded text descriptions. PNG supports full-color images and can be used for photographic images. However, because it uses lossless compression, the resulting file is much larger than with lossy jpeg compression. Like GIF, PNG does best with line art, text, and logos—images that contain large areas of homogenous color with sharp transitions between colors. Images of this type saved in the PNG format look good and have a similar or even smaller file size than when saved as gifs. However, widespread adoption of the PNG format has been slow. This is due in part to inconsistent support in web browsers. In particular, Internet Explorer does not fully support all the features of PNG graphics. As a result, most images that would be suitable for PNG compression use the gif format instead, which has the benefit of full and consistent browser support. VIII. TIFF Graphics. Tagged Image File Format. This is a flexible format that normally saves eight bits or sixteen bits per color red, green and blue for 24-bit and 48-bit totals, respectively, usually using either the TIFF or TIF filename extension. The tagged structure was designed to be easily extendible, and many vendors have introduced proprietary special-purpose tags with the result that no one reader handles every flavor of TIFF file. TIFFs can be lossy and lossless; some offer relatively good lossless compression for bi-level (black and white) images. TIFF image format is not widely supported by web browsers. TIFF remains widely accepted as a photograph file standard in the printing business. TIFF can handle device-specific color spaces. OCR-Optical Character Recognition-software packages commonly generate some form of TIFF image often monochromatic for scanned text pages. IX. RIF Graphics. This refers to Raw Image Formats that are available on some digital cameras, rather than to a specific format. These formats usually use a lossless or nearly lossless compression, and produce file sizes smaller than the TIFF formats. Although there is a standard raw image format, the raw formats used by most cameras are not standardized or documented, and differ among camera manufacturers. Most camera manufacturers have their own software for decoding or developing their raw file format, but there are also many third-party raw file converter applications available that accept raw files from most digital cameras. Some graphic programs and image editors may not accept some or all raw file formats, and some older ones have been effectively orphaned already. X. BPG Graphics. Better Portable Graphics is a new image format. Its purpose is to replace the JPEG image format when quality or file size is an issue. Its main advantages are: i. High compression ratio. Files are much smaller than JPEG for similar quality. ii. Supported by most Web browsers. iii. Based on a subset of the HEVC open video compression standard. iv. Supports the same Chroma formats as JPEG to reduce the losses during the conversion. v. Native support of 8 to 14 bits per channel for a higher dynamic range. vi. Lossless compression is supported. vii. Various meta data such as EXIF can be included 2. Explain the difference between Vector Graphics and Bitmap Graphics. VI. Photo-Realism Because it is comprised of small pixels, the bitmap is the most suitable format for photo-realistic images or images with high amounts of fine detail. Because each pixel can represent any one of the more than 16 million different colors that can be displayed by most computer monitors, the bitmap image is able to imitate the subtle color variations of a photograph. The vector image, on the other hand, does not possess the same kinds of photo-realistic capabilities. Because it is comprised of larger objects the vector image cannot achieve the kind of fine detail that is necessary for photo-realism. Instead, vector images tend to have a more cartoon-like appearance, for example clip-art images. Thus, since photo-realism is unachievable when using vector images, the bitmap is the standard format for working with digital or scanned photographs. VII. Scalability When it comes to being able to make an image larger or smaller without any loss in quality, the vector image is undoubtedly the superior format. Because the vector image is comprised of mathematically defined objects, rather than by a pre-ordered pattern of pixels, its size can be easily manipulated with little or no loss in the quality of the image. The objects within the image are simply re-rendered at a greater or smaller scale, providing consistently smooth edges at any size. Bitmaps, on the other hand, are more difficult to scale, because changing the size of a bitmap requires a complete rearrangement of the pixels. Many graphics programs do an excellent job of reducing bitmaps, but enlargements always result in a loss of quality. An enlarged bitmap is likely to appear blurry, or even pixelated, meaning that the different pixels of the image have become visible. VIII. Shape A bitmap always has four straight edges. It cannot be elliptical, triangular or any other shape other than a rectangle. This obviously presents certain difficulties when attempting to lay one non-rectangular image over another, or when publishing an image to the internet when the background of the image is not the same as the background of the website. Certain efforts have been made to rectify this problem, such as the transparency option available to GIF bitmaps, but for the most part, the rectangular nature of the image remains a disadvantage to bitmaps. The vector image, on the other hand, is much more versatile. It can be any shape, from simple geometric forms to many of the most complicated and most abstract forms imaginable. This eliminates the problem of having a rectangular background around a non-rectangular image. IX. Conversions Converting from one bitmap format to another bitmap format is a very simple process, which can generally be achieved through a simple “Save As” command and the software will make all the conversions itself. Converting between vector types generally involves a similar process, although there is a more frequent loss of quality during vector type conversions than during bitmap type conversions. Converting from vector to bitmap is also a simple process which generally yields excellent results. However, converting from bitmap to vector is more difficult as pixels have to be converted into algorithms. X. File Size While file size does not affect the quality of the image, it is still a concern, especially when images are being transferred over the internet or carried on floppy disks. Unfortunately, it is impossible to say that either vector or bitmap images are smaller than other, as their size is dependent on certain variable factors. For Bitmap images, the most important determinant for file size is the proportions of the image itself. The larger the image, the more pixels it contains and, thus, the larger the file size. The size of vector graphics files is not dependent on the size of the image, but on its complexity. The more objects there are in a vector, the more algorithms it will need to contain in order to render those objects, and the larger the file will become. This means that a large image comprised of a few objects will have a smaller file size than a small image comprised of numerous objects. 3. 4. Describe why JPEG is the preferred choice for websites. I. The JPEG file format has been around for many years, and is supported by every image editor and web browser on the market. It is also supported by every digital camera, and any video camcorder that can also take pictures. Every digital photo print shop also supports the JPEG standard. II. They do not take up much storage space. III. The compression algorithm is lossy, which means data is discarded when the file is compressed. For the most part, however, you won’t notice any loss of data unless you start to edit the file. IV. The more compression you use, the more artifacts may appear. V. All the settings from the digital camera have already been applied to the JPEG. This can be a downside if, for example, you had the wrong colour balance set, then your digital pictures would have a colour cast to them. 5. 6. Clearly justify which technique (lossy or Lossless) is more suitable by giving reasons. The advantage of lossy methods over lossless methods is that in some cases a lossy method can produce a much smaller compressed file than any lossless method, while still meeting the requirements of the application. Lossy methods are most often used for compressing sound, images or videos. This is because these types of data are intended for human interpretation where the mind can easily see past very minor errors or inconsistencies. I. Transparency. When a user acquires a lossily compressed file, the retrieved file can be quite different from the original at the bit level while being indistinguishable to the human ear or eye for most practical purposes. Many compression methods focus on the idiosyncrasies of human physiology, taking into account, for instance, that the human eye can see only certain wavelengths of light. The psychoacoustic model describes how sound can be highly compressed without degrading perceived quality. Flaws caused by lossy compression that are noticeable to the human eye or ear are known as compression artifacts. II. Compression ratio. The compression ratio that is, the size of the compressed file compared to that of the uncompressed file of lossy video codecs is nearly always far superior to that of the audio and still-image equivalents. Still images are often lossily compressed, but the quality loss is more noticeable, especially on closer inspection. III. Transcoding and editing An important caveat about lossy compression (formally transcoding), is that editing lossily compressed files causes digital generation loss from the re-encoding. This can be avoided by only producing lossy files from (lossless) originals and only editing (copies of) original files, such as images in raw image format instead of JPEG. If data which has been compressed lossily is decoded and compressed losslessly, the size of the result can be comparable with the size of the data before lossy compression, but the data already lost cannot be recovered. When deciding to use lossy conversion without keeping the original, one should remember that format conversion may be needed in the future to achieve compatibility with software or devices (format shifting), or to avoid paying patent royalties for decoding or distribution of compressed files. References Trussell H &Vrhel M (2008). "Introduction". Fundamental of Digital Imaging: 1–6. ”The Birth of Digital Phototelegraphy”, the papers of Technical Meeting in History of Electrical Engineering IEEE, Vol. HEE-03, No. 9-12, pp 7-12 (2003) Cherry, Michael; Edward Imwinkelried (2006). Read More