Presentation on theme: "What is digital resolution all about? Jellybean portrait shows us how units of color placed together make an image."— Presentation transcript:
What is digital resolution all about? Jellybean portrait shows us how units of color placed together make an image.
Pixels & resolution A digital image, just like the image you see on your computer monitor or television, is made up tiny squares called pixels. The term Resolution, when used to describe a digital camera refers to the size of the digital image the camera produces, and is usually expressed in terms of megapixels - how many million pixels it can record in a single image. The number of pixels a camera captures is called the camera's resolution.
Pixels Pixels are the building blocks of every digital image. Clearly defined squares of light and color data are stacked up next to one another both horizontally and vertically. Each picture element (pixel for short) has a dark to light value from 0 (solid black} to 255 (pure white). That is, there are 256 defined values. Fine detail is rendered by having many, many of these pixels. Too few and the picture appears jagged.... or pixelated as above photo.
Megapixels A camera that captures 1600 x 1200 pixels produces an image with a resolution of 1.92 million pixels and would be referred to as a 2.0 megapixel camera. You get to 1.92 million pixels by multiplying the vertical and horizontal dimensions. That number is then rounded off to 2 for marketing purposes. 1600px 1200px 1600 x1200 1,920,000
The image below shows the relative image sizes of some common digital cameras. The actual size even the smallest of them would likely be larger than your entire computer screen. Notice the tremendous difference between 2.1 megapixels and 3.3 megapixels. You'll get better prints from a 3 megapixel camera when compared to a 2 megapixel camera. This example gives you a feeling for the size relationship of images recorded at 1.3 through 5.0 megapixels. As you can see a jump from 1.3 to just 3.3 megapixels is significant.
Advantage to high resolution More pixels to work with Better print quality - Starting with a higher resolution image means there's less magnification necessary to get to a given print size. You can crop the image if you need to. Cropping is when you only use part of the image for the final print. The more you have to enlarge the image, the more any defects will start to jump out.
Disadvantage to high resolution More pixels to work with - Large file size, slower downloading time on the web or in an email. Some emails have a limit to the size they can send. Storage for files needs to be considered. If you are not printing, you may not need to keep a large file.
Printing vs. Screen Digital images NEED to be packed tighter for printing that for viewing on a computer screen. 72ppi 300ppi
Why? Computer monitors display images at 72 ppi (pixels per inch), meaning that there are 72 pixels for every 1 inch of linear screen space you see on your screen. Therefore, if you have an image on the screen that is 720 pixels wide, it will take up 10 inches of linear screen space (72 dpi x 10 inches = 720 pixels). This may look beautiful on the screen, but if you try to print this image on a printer at 72 dpi the result will look extremely choppy and jagged.
Get a good Print To get a good looking print from your printer you'll need to print at 300 ppi (pixels per inch), which means that the 10 inches across the screen will be reduced to only 2.4 inches on paper (720 / 300 = 2.4, or 24% of the original 10 inches). The result is a smaller, but much cleaner, image on paper. So a good rule of thumb about how physically big an image will be on paper is that it will be about 25% or one quarter of it's size on your screen shown full size (100%). It is important to remember that you can zoom which may not accurately reflect the size.
Sizes Common Image Sizes and Print Sizes at 300 dpi* Image sizeMegapixelsPrint size 4064 x 2704 11.1 13.5 x 9 3088 x 2056 6.3 10.25 x 6.8 3008 x 1960 5.3 10 x 6.5 2048 x 1536 3.0 6.8 x 5.1 1600 x 1200 2.0 5.3 x 4 1280 x 960 1.2 4.25 x 3.2 640 x 480 0.03 2.1 x 1.6 DPI - Dots per inch, a printing term PPI - Pixels per inch, a digital screen term
PPI vs DPI Dots per inch DPI - are tiny ■ per inch PPI - are tiny squares
No stretching There is true resolution and interpolation. Interpolation is the process of "stretching" a digital image by adding pixels that were not there originally. Since every pixel must have a color, this process usually involves assigning an intermediate color to the "invented" pixels based upon the colors of the pre-existing pixels surrounding the new ones.
Less clarity The result is a larger image in terms of resolution, but one that now has less clarity because you simply cannot produce something from nothing. Interpolation is most common on low dollar, entry-level digital cameras. Just keep in mind the lower the real resolution the fuzzier the interpolated image will be.
Count the pixels 5 megapixel image has the dimensions of 2560 x 1920 pixels. 4 megapixel image has the dimensions of 2272 x 1704 pixels. 3 megapixel image has the resolution of 2048 x 1536. 2 megapixel image has the resolution of 1600 x 1200, 1 megapixel image has the dimensions of 1280 x 960 pixels.