INTRODUCTION
• Resolution is the measurement of how many dots/pixels fit into one inch.
• The higher resolution, the sharper the image will be.
• Recommends resolution: 300 dpi (dots per inch) for crisp, clear results.
• Lower resolution images appear fuzzy, jagged and blurry.
RULES TO REMEMBER
• Images for printing should be 300 dpi (dots per inch) at the final size in the layout.
• Images which include text should be 400 dpi at the final size in the layout.
• Resolution and image size are inversely proportional to each other.
• Enlarge an image, the resolution decreases; reduce an image, the resolution increases.
– Example: a 2 x 2" image at 300 dpi (acceptable) enlarged to 4 x 4" has a new resolution of 150 dpi (unacceptable).
• 2 x 2" image @ 300 dpi = GOOD
• ...enlarged to 4 x 4" = 150 dpi = BAD
• 17 x 13" image @ 72 dpi = BAD
• ...reduced to 4 x 3" = 300 dpi = GOOD
THINGS TO AVOID
• Web images are predominately low resolution (72-96 dpi) GIF or JPEG files.
• This resolution is good for quick transmission over the internet, but is not acceptable for use in printing.
• Do not save images or graphics from a website to use in your print project!
PRINT SIZE
• The maximum print size that a digital camera can produce is directly related to the number of pixels on the camera's CCD (the resolution)
Image Size/Resolution Calculator
FORMULA
• Convert pixels to inches (Output to Monitors/Printers) Pixels / DPI = Inches
CALCULATING PRINT SIZE
• You can calculate what printed image size you can safely achieve from the dimensions of the original image
• A 3,000 by 2,000 pixel image from a 6- megapixel camera printed at 300 dpi will be 10 inches across the horizontal axis (3,000 divided by 300).
• Looking at this from another viewpoint, a 1,500 by 1,000 pixel image printed at a size of 10 inches ill be printing at a resol tion of 150 dpi will resolution (1,500 divided by 10).
WHAT IS SCALING
• Scaling is an extremely important working tool for printing.
• There are two ways to scale an image, either during the scan, or after the scan.
• The next page covers scaling AFTER the scan.
SCALING TO PRINT A DIFFERENT SIZE
• The practical way scaling is used AFTER the scan is this:
– We have an image we want to print.
– It has a size in pixels, perhaps 1200 x 800 pixel.
– We want to specify a printed size in inches.
– We specify a scaled resolution to accomplish that.
• Resolution dpi = (pixels of length) / (inches of
length).
• Suppose our image is 1200 pixels wide. Contemplating printing it, we see that we could print this image at several different sizes, simply by changing the scaled resolution
• Example…..
• 1200 pixels / 10 inches = 120 dpi
• 1200 pixels / 8 inches = 150 dpi
• 1200 pixels / 6 inches = 200 dpi
• 1200 pixels / 4 inches = 300 dpi
• 1200 pixels / 3 inches = 400 dpi
• 1200 pixels / 2 inches = 600 dpi
• Resolution dpi = (pixels of length) / (inches of length). Pixels/DPI=Inches
• This is scaling, the easy way (lying to the printer…)
• Given the available image size and the available printer's resolution needs and capability, you pick the best choice for your purpose, balancing resolution against image size.
REQUIREMENTS: PRINT
• Resolution must be high
• 300 DPI for micrographs, and similar photographic-type images.
• 600 DPI for images like graphs and drawings.
• Color - Printing is done in CMYK.
• Colors outside CMYK’s gamut will not be printed.
• Remember, CMYK’s gamut is smaller than RGB’s.
• This can lead to loss of image detail when viewing the printed image if the source was in RGB.
REQUIREMENTS: ONLINE
• Resolution does not need to be very high
• Monitors display at 72 - 96 DPI, so 100-200 DPI is plenty for any kind of figure
• More than 200 DPI is overkill
• the files become very large.
• They may not display properly on a monitor.
• Color – Monitors display in RGB
• RGB contains almost all of CMYK’s colors.
• Most images, whether in RGB or CMYK format, will display color properly in online media.
PPI or DPI
• Pixels per inch (ppi) is often (although mistakenly) used interchangeably with dots per inch (dpi)
• Dots per inch (dpi) is a measurement describing the way an image is printed, scanned, or displayed on your monitor. For instance, you may scan an image at 300 dpi, print a 300 dpi image at 600 dpi, view it on your monitor at 72 dpi, but unless you resample it in Photoshop, the image will always have a resolution of 300 ppi
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