Dynamite Digital Images: A Primer by Melodie Putnam Oregon State University

Outline  Basics of digital photography  Resolution  File format  Editing: cropping  Focus  Lighting

Goal: To provide an image which allows identification of the subject

Resolution (optical sharpness) Of camera: Number of photosites (pixels) 1600 columns x 1200 rows = 1.92 x 10 6 = 2 megapixel camera Nikon Coolpix 8800 = 3,264 x 2,448 pixels (8 Mp) to 1,280 x 960 (1 Mp)

Resolution Of monitor: Pixels per linear inch = ppi Computer monitor = ppi Images at 72 ppi on the computer will look about the same as images > 72 ppi

300 ppi 9 Mp 72 ppi 156 Kp difference = ability to enlarge

Resolution Of printer: Good quality = 300 ppi

Viewing images on screen If 1 monitor pixel = 1 image pixel then image is displayed at 100% (even if entire image is not on the screen)

File compression 1 pixel can have up to 24 bits of color 24 bits x 1,600 x 1,200 pixels = ~ 6 Mb Color images are large files! Compression saves space Joint Photographic Experts Group (JPEG)

Poor image resolution

File format Tagged Image File Format (TIFF) = standard for lossless compression (or no compression) JPEG = compressed images (may be losses)

Editing - Save files to be edited as TIFF files opening and saving images with compression will result in cumulative compression (losses) each time

Editing Crop the image to clarify

Editing - Save files as TIFF files - Crop, frame, and edit - Save edited version as jpeg files

Focus Autofocus Works best with contrast between subject and background

Focus Autofocus Does NOT work well: - Subject is same color as background - Objects are different distances from camera

Manual focus Use with close-ups Use when subjects are at difference distances

Lighting Avoid harsh light that produces shadows Images that are too dark mask details Watch background glare

Washed out & out of focus

Background  Avoid white  Lighter backgrounds for dark subjects  Darker backgrounds for light subjects

Add a size reference (ruler is best)

Size reference is OK, but camera is too far away

Saving images - Give your image a descriptive name e.g. “pumpkin stem Walters farm ” vs. DSCN0347

Finally, Critically review your images before sending them. If images are: - out of focus - cluttered - poorly lit - not illustrative of the situation, problem or pest - too far away… Don’t expect a diagnosis

Authorship Melodie Putnam Director, Oregon State University Plant Clinic 1089 Cordley Hall 2701 SW Campus Way Corvallis, OR Phone: Fax: bpp/Plant_Clinic/index.htm

National Plant Diagnostic Network Thank you!