Presentation on theme: "Photoshop Software Rasterized, file formats, and printing choices."— Presentation transcript:
Photoshop Software Rasterized, file formats, and printing choices
Photoshop is a raster program What is raster program like Photoshop? Programs that use pixel colors to create a graphic. A raster graphic is an image made of hundreds (or thousands or millions) of tiny squares of color information, referred to as either pixels or dots. (Technically pixels refer to color blocks viewed on an electronic monitor where as dots refer to the ink dots on a printed piece. But even professional designers, myself induced, often use these two terms interchangeably.) The most common type of raster graphic? A photograph. The designer’s preferred program for creating and editing raster files? You guessed it: Adobe Photoshop. Popular raster file format extensions include: jpg/jpeg, psd, png, tiff, bmp and gif.
What is a pixel? A pixel is a small dot of color either RBG (primary colors of light). All lighted display devices are made of pixels. Digital Cameras have a sensor that collects color data and make an image file that contains a variety of color pixel data. http://www.youtube.com/watch ?v=uRzPBELMemM
PPI or DPI/resolution PPI stands for Pixel per inch. DPI stands for Dots per inch. Image is measured in the amount of pixels in a square inch. The smaller the ppi the lower the image quality, 72 ppi is average web image size. The high ppi like 300, offers better image quality and more options for printing.
Monitor Pixels A video monitor with 215,500 pixels can display 1024x768 (786,432 pixels),when used as computer monitor.
Pros of Raster Images Rich Detail: Ever wondered what the term “dpi” stands for? It means “dots per inch,” a measurement of how much detailed color information a raster image contains. Say you’ve got a 1” x 1” square image at 300 dpi—that’s 300 individual squares of color that provide precise shading and detail in your photograph. The more dpi your image contains, the more subtle details will be noticeable. Precise Editing: All of those individual pixels of color information can also be modified, one by one. So if you’re a true perfectionist, the level of editing and customization available in a raster image is almost limitless. Cons of Raster Images Blurry When Enlarged: The biggest downfall to raster images is that they become pixelated (aka grainy) when enlarged. Why is this? Well, there are a finite number of pixels in all raster images; when you enlarge a photo, the computer takes its best guess as to what specific colors should fill in the gaps. This interpolation of data causes the image to appear blurry since the computer has no way of knowing the exact shade of colors that should be inserted. Large File Size: Remember how a 1” x 1” square at 300 dpi will have 300 individual points of color information for the computer to remember? Well let’s say you have an 18” x 24” photo— that’s 129,600 bits o’ info for a computer to process which can quickly slow down even the faster machine.
File Formats RAW, TIFF, JPEG, PNG, PDF, GIF… Why so many file formats? When to use them?
Bayer Interpolation A Bayer filter mosaic is a color filter array (CFA) for arranging RGB color filters on a square grid of photosensors. Its particular arrangement of color filters is used in most single-chip digital image sensors used in digital cameras, camcorders, and scanners to create a color image. The filter pattern is 50% green, 25% red and 25% blue, hence is also called RGBG, GRGB, or RGGB. Resources from Wikipedia and http://www.kenrockwell.com/tech/bayer.htm
JPEG- (Joint Photographic Experts Group) Jpeg format is used for color photographs, or any pictures with many blends or gradients. It is not good with sharp edges and tends to blur them a bit. This format became popular with the invention of the digital camera. Every time image is save it goes through Lossy Compression, which reduces the amount of info in the image, lowing the image quality. The amount of compression every time opened and save results in loss of original info and quality. TIFF-( Tagged Image File Format) This file format has not been updated since 1992. It can store an image and data (tag) in the one file. TIFF also stores files with virtually no compression and therefore is good for storing images that need to be edited and re- saved without suffering a compression loss. RAW is the output from each of the original red, green and blue sensitive pixels of the image sensor, after being read out of the array by the array electronics and passing through an analog to digital converter.
PDF-Portable Document Format was developed in the early 1990s as a way to share documents, including text formatting and inline images, among computer users of disparate platforms who may not have access to mutually-compatible application software. The format is a like a screen shot but with the ability to have clickable links and buttons, form fields, video, and audio. Made for online use and can be compressed but doesn’t do it automatically. PNG -Portable Networks Graphic) Apparently this is one of the best image formats, however it was not always compatible with all web browsers or image software. GIF-(Graphics Interchange Format) Gif format is best used for text, line drawings, screen shots, cartoons, and animations. It is commonly used for fast loading web pages.