ADAPTING DIGITAL IMAGES
by Keith Lightbody - Facilities Consultant - last updated 5 March 2007
Short notes on how to adjust a digital camera image to suit different
purposes:
for PRINT |
for EMAIL |
for WEB |
|
Suitable digital camera setting: | maximum quality | mid range quality | minimum quality |
Suitable scan resolution: | 300 dpi | 150 dpi | 72 dpi |
Recommended digital camera | > 3 Megapixels | 1 - 2 Megapixels | any model |
Suitable digital camera setting: | maximum quality | mid range quality | minimum quality |
Typical file size: | > 1 MB | 100 K to 1 MB | < 100 K |
Typical image size: | 25 cm x 20 cm | 10 cm x 8 cm | 5 cm x 4 cm |
Typical pixel size: | 2000 x 1500 pixels | 800 x 600 pixels | 400 x 300 pixels |
Note: for EMAIL via a 56 K modem (or slower) follow the instructions for WEB
INSTRUCTIONS FOR OUTPUT TO PRINT
1. Ensure digital camera settings are on best possible quality or scanner settings
are on at least 300 dpi (dots per inch)
2. Consider using a tripod for maximum sharpness of image (unsteady hands can
cause blur - reduce quality)
3. Open the digital picture in image editing software (e.g. Photoshop - any
version)
4. Save as a new file in an uncompressed format (e.g. bigimage.psd)
5. Crop
the image to keep only the important parts, save again
6. Adjust curves, colour, brightness or contrast if necessary, save again
7. Carefully clone
out any problems or distractions, save again
8. Save in an alternative uncompressed format if required (e.g. bigimage.tif)
9. Use this image for any PRINT tasks
THE HIGH QUALITY PRINT IMAGE CAN ALSO BE USED FOR OTHER PURPOSES IF THE FILE SIZE IS REDUCED - THIS INVOLVES A LOSS IN IMAGE QUALITY: SMALLER FILE SIZE = LOWER QUALITY.
NOTE 1: Clicking on an image and using the RESIZE 'handles' to make it display
in a smaller amount of space does not reduce the file size! You
typically need to use image editing software - see instructions below.
NOTE 2: Setting your camera on maximum resolution for images only to
be used in web pages is very inefficient - only choose maximum settings
if you may also require print versions.
INSTRUCTIONS FOR OUTPUT TO EMAIL USING PHOTOSHOP
1. open the image in Photoshop (FILE - OPEN or drag-and-drop image on to Photoshop
shortcut or alias)
2. choose IMAGE - IMAGE SIZE, check that is showing RESOLUTION: 72 pixels/inch,
check tick for CONSTRAIN PROPORTIONS and tick for RESAMPLE IMAGE, reduce either
PIXEL height or CENTIMETRE height (see examples in the table above)
3. choose FILE - SAVE AS... make sure you choose SAVE IN: chosen location, FILE
NAME: short meaningful name, FORMAT: JPEG (*.jpg)
5. select JPEG Options: High (good quality) or Maximum (best quality but larger
file size)
4. Close Photoshop
5. Confirm the file size is in range 100 K to 1 MB
INSTRUCTIONS FOR OUTPUT TO WEB PAGE USING PHOTOSHOP
1. open the image in Photoshop (FILE - OPEN or drag-and-drop image on to Photoshop
shortcut or alias)
2. choose IMAGE - IMAGE SIZE, check that is showing RESOLUTION: 72 pixels/inch,
check tick for CONSTRAIN PROPORTIONS and tick for RESAMPLE IMAGE, then
significantly reduce either PIXEL height or CENTIMETRE height (see
examples in table above), for web pages it usually looks better if adjacent
images have the same height.
3. choose FILE - SAVE AS... make sure you choose SAVE IN: (chosen location),
FILE NAME: (short meaningful name), FORMAT: JPEG (*.jpg)
4 . select JPEG Options: Medium (reasonable quality with smaller file size)
5. Close Photoshop
6. Confirm the file size is less than 100 K
7. Confirm the file opens in a web browser (e.g. Internet Explorer)
Download a simple image to try out some of the above ideas: ehorse.jpg epark.jpg (each image approx 100 k)
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