Screen and image resolution


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  • 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.
  • Screen and image resolution

    1. 1. 2.01 Investigate graphic image design.
    2. 2. Types of Images <ul><li>Clip Art – premade graphics that are available online and in many software packages; may be vector or raster. </li></ul><ul><li>Photographs – raster images that contain millions of colors. </li></ul><ul><li>Art Work – computer created drawings or paintings; may be raster or vector. </li></ul><ul><li>Which type of image is appropriate? </li></ul><ul><li>Select images that reflect the purpose and theme of the document. </li></ul><ul><li>Use images to convey meaning and communicate, not to decorate. </li></ul>1.02 Investigate image editing.
    3. 3. The quality of an image is dependent upon two factors: <ul><ul><li>Resolution </li></ul></ul><ul><ul><li>Aspect Ratio </li></ul></ul>1.02 Investigate image editing.
    4. 4. Image Resolution <ul><li>Measured in PPI, or pixels per inch. </li></ul><ul><li>PPI is the numbers of pixels contained in one inch. </li></ul><ul><ul><li>The higher the PPI, the better the quality. </li></ul></ul><ul><ul><li>The higher the PPI, the larger the file size. </li></ul></ul><ul><li>Match the quality to the delivery method. </li></ul><ul><ul><li>Most monitors can only display 72 PPI, so images that will be displayed on a monitor do not need a higher PPI. </li></ul></ul><ul><ul><li>Printers can print in much more detail so printed images need to contain more pixels per inch. </li></ul></ul>
    5. 5. Types of Resolution <ul><li>PPI – pixels per inch </li></ul><ul><ul><li>The number of pixels in an image. </li></ul></ul><ul><li>DPI – dots per inch printed by a printer. </li></ul><ul><ul><li>Dots of ink or toner in a printed image </li></ul></ul><ul><ul><li>The lower the DPI of a printer, the less detailed the image will be. </li></ul></ul><ul><ul><ul><li>150 PPI is sufficient for most personal desktop printers. </li></ul></ul></ul><ul><ul><ul><li>300 PPI is better for high-quality images printed on more sophisticated printers. </li></ul></ul></ul>1.02 Investigate image editing.
    6. 6. Monitor Resolution 1024x768 Industry Standard 640x480 1.02 Investigate image editing. <ul><li>Also measured in PPI. </li></ul><ul><li>Refers to the number of pixels per inch displayed on a monitor. </li></ul><ul><li>The higher the resolution, the higher the level of detail </li></ul><ul><li>As resolution is increased on the monitor, detail is emphasized and image size is reduced </li></ul>
    7. 7. Aspect Ratio <ul><li>Aspect Ratio – relationship of an object’s width to its height </li></ul><ul><li>What’s the answer? </li></ul><ul><ul><li>An original image that is 1”x 1” has a resolution of 100 PPI </li></ul></ul><ul><ul><li>What is the effect on the resolution of enlarging the image to 2”x 2”? </li></ul></ul><ul><ul><ul><li>What happens to the image quality? </li></ul></ul></ul>1.02 Investigate image editing.
    8. 8. Resizing a Raster Image <ul><li>A small image that is enlarged is easily distorted. </li></ul><ul><li>Pixels are not added, just enlarged </li></ul><ul><li>Better to start with a large image and make it smaller </li></ul><ul><ul><li>File size will remain the same </li></ul></ul><ul><ul><li>An image must be edited to reduce file size. </li></ul></ul>1.02 Investigate image editing.