The document discusses different types of images, image resolution, and aspect ratio. It explains that images can be vector, raster, or photographs. Resolution is measured in pixels per inch (PPI) and dots per inch (DPI) printed, with higher resolution images having more detail but larger file sizes. Aspect ratio refers to an image's width to height. Enlarging an image reduces its resolution and quality, as pixels are enlarged but not added.
Teacher Note: The purpose of any business document is to convey a message. Students should make sure any images they use help them to convey their message. If they do not make the message easier to understand, then they are confusing the message and should not be used.
Teacher Note: Graphics displayed on a computer monitor can be set to 72 PPI because most monitors will only display 72 PPI. However, you need higher resolutions for printing images. 150 PPI is sufficient for desktop printing; 300 PPI for high quality printing. However, the larger the PPI, the larger the file size will become.
Suppose an image has a resolution of 100 pixels per square inch and is 1 inch square. If you resize the image so that it is two inches square, it becomes 50 pixels per inch which reduces the resolution by half and also reduces the image quality. The same number of pixels is still in the image but the display area is larger. Therefore, you will see pixelation because each pixel in the image must cover a larger space on the screen.
You will notice that by stretching an image to make it larger, it gets fuzzy and distorted. This is because the computer just makes a really small square (pixel) of data larger or wider to cover more space on the computer screen. The end result is a distorted image. For this reason, it is easier to start with a large image and make it smaller than to try to make a small image larger than its original size. Remember: Compare the two images. If you were to compare the properties of both images, (by right clicking and scrolling down to properties on each image) you would see that it is the same image, but more importantly they have the same file size, although one is a lot bigger than the other.
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