Presentation on theme: "Digital Image Resolution Image Resolution Preparing Digital Images For press or monitor presentation."— Presentation transcript:
Digital Image Resolution Image Resolution Preparing Digital Images For press or monitor presentation
Digital Image Resolution What is Resolution & Why is it important? Resolution refers to the number of pixels in a digital image. As a designer, you may need to prepare images for newsletters, magazines, newspapers, or web sites. -Printing images with the wrong resolution will result in poor quality. -Placing images on a web site with the wrong resolution may increase file size and download time.
Digital Image Resolution Review In the previous lesson, digital Images were described as being created from a series of bits and bytes that form pixels. The number of pixels displayed in an image is counted in pixels per inch, PPI. The greater the number of pixels in an image, the greater the clarity and file size. 5 ppi 1 25 ppi 1 72 ppi 1 10 ppi 1
Digital Image Resolution Resolution & money Resolution is a little like money… depending on who you talk to, it is has different names. In the United States, the dollar is a standard unit of money. In Japan, the yen In Switzerland, the franc Each country has its own vocabulary and value system for counting money. Like money, resolution also has different names and values to different people.
Digital Image Resolution Resolution Vocabulary & Value Lines Per Inch - LPI Used by printers to create halftone print screens. Pixels Per Inch - PPI Used by designers to manipulate digital images Dots Per Inch - DPI Used by desktop printers to count how many dots of ink are used per inch. 25 ppi 1 If you want to get really technical, true resolution is measured in SPI, Samples Per Inch. However, this is rarely seen in most software applications that work with digital images.
Digital Image Resolution LPI - Lines Per Inch When sending information to a printer, You need to speak printer language. What is the LPI resolution for this job? Your printer will be very impressed! LPI converts digital images into halftone images that are needed for printing newspapers, magazines, etc. You need to know how PPI images convert to LPI images… like yen converts to dollars Resolution Vocabulary & Value 72 ppi digital image B & W halftone Color halftone
Digital Image Resolution PPI digital image conversion to LPI halftone image for printing. When asking the question, What is the LPI resolution for this job? Here is what your printer will likely tell you. Resolution Vocabulary & Value 72 ppi digital image B & W halftone Color halftone
Digital Image Resolution What does this mean to the PPI of the digital Image? In order to have a quality image printed, the PPI resolution of the digital image must be twice the printers LPI resolution. Resolution Vocabulary & Value 300 ppi digital image Acceptable color halftone
Digital Image Resolution You need to send digital files to your yearbook company for printing the yearbook. Your yearbook representative informs you they print at 133 LPI resolution. Knowing you need to double the LPI resolution to determine the PPI resolution for your digital images, you determine you need to save your digital images at 266 PPI. (They may want you to round up to 300 to be on the safe side.) Resolution Yearbook Example
Digital Image Resolution If you sent your digital image in with a low PPI resolution, you would receive a poor quality image when printed. If you sent your digital image in with the correct PPI resolution, you would receive a quality image when printed. Resolution Yearbook Example 72 ppi digital imagePoor quality halftone 266 ppi digital imageQuality halftone Note: On your monitor, a 72 ppi image will often look as good as a 266 ppi image. This is because your monitors display is only 72 ppi.
Digital Image Resolution The resolution for any image you plan to view on a monitor, I.e. web page or television, should always be 72 ppi. There is rarely a need for anything better. Resolution Web Example 72 ppi digital image
Digital Image Resolution Preparing image Resolution Helpful tips Know the end use of an image when creating the image. (Digital photo or scan) Create images at a higher resolution than needed. You can easily reduce the image resolution, but increasing the resolution is a slippery slope. Use the chart in the assignment sheet. Relationship of mega pixel settings and end use of image.
Digital Image Resolution Preparing image Resolution Change image resolution and size in a paint application like PhotoShop With the image open in PhotoShop, select from the menu, Image followed by Image Size. This will display the Image size dialogue box. Most paint programs will automatically open a new image at 72ppi This is a very big file.
Digital Image Resolution Resizing vs. Resampling Resizing an image involves changing the print dimensions without changing the total pixel dimensions. As the resolution is increased, the print size becomes smaller, and vice versa. Resampling, however, involves changing the pixel dimensions and will always introduce a loss in quality. 1st Change Resolution To change the resolution to 300, make sure the Resample Image is deselected. This will automatically change the document size also. Preparing image Resolution & size
Digital Image Resolution Resizing vs. Resampling Resizing an image involves changing the print dimensions without changing the total pixel dimensions. As the resolution is increased, the print size becomes smaller, and vice versa. Resampling, however, involves changing the pixel dimensions and will always introduce a loss in quality. Preparing image Resolution & size 2nd Change to desired document size To change the document size, select Resample Image and change the width to desired document size
Digital Image Resolution Files to be printed save as Tif files There is little information lost in Tiff files and printers like to work with them. Files to be place on the web save as Jpg files Jpg files are compressed for small file size and faster down loading. Information is lost in the file through compression, so image quality does suffer a little Saving files