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 crop tool icon the image to keep only the important parts, save again
6. Adjust curves, colour, brightness or contrast if necessary, save again
7. Carefully clone clone tool icon 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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