Digital Photo Correction & Manipulation

Tonya Hines, CMICertified Medical IllustratorArt Director, Mayfield Clinic

Today you will learn

Resolution What is dpi? How much resolution for specific uses

File formats jpg, gif, tif, pdf, psd Which file format to use and why

How to correct and manipulate Color photos Newspaper clippings Diagnostic scans (MRI, CT, angio)

If you only learn 1 thing!

Relationship of resolution and image size

garbage in = garbage out

Digital imaging

Image capture: steps taken to digitize an image

Image correction: steps taken to correct hardware interference with color and resolution

Image manipulation: steps taken to artistically change an image for a desired effect

Before you acquire images

What is the final use of the image? On-screen/web (PowerPoint, MySpace, email,

wallpaper, digital photo frame) Laser or inkjet prints (scrapbooks, handouts) Photo printing or publication

Answer tells us Resolution and file size needed Best method to capture it

shopping without knowing shirt size

72 dpi 150 dpi

What is resolution?

Number of pixels per inch (blocks of color or gray that make a picture)

More pixels per inch = higher res = more detail

But also = bigger file size!

pixel per inch (ppi)= dot per inch (dpi)

Resolution & image size are directly proportional

=20 Mb file

8” x 10”300dpi

41.6” x 33.3”72dpi

2400 pixels

2400 pixels

3000

pix

els

3000

pix

els

Resolution & image size are directly proportional

20 Mb file > 1.2 Mb file

8” x 10”300dpi

8” x 10”72dpi

2400 pixels

3000

pix

els

576 pixels

720

pixe

ls

Why would I ever want small file size?

Reduce system resources and time in processing and printing

Too large to email as an attachment Fill up recipients email boxes (over quota) Maximize storage

More resolution beyond your purpose is waste

bigger is not always better

Resolution is

Height x width

Dots per inch

File size

Resolution by usage/output

Output or printer DPI needed

Web 72

Computer monitor 96

Black and white laser printer 150

Color inkjet printer 150 - 220

Photo inkjet printer 220 - 300

Newspaper 100 - 150

Offset printing (brochures, books) 266 - 350

don’t confuse image res with printer res

Common resolutions

Usage dpi file size

PowerPoint10” x 7.5” 96 1.98 MB

Laser / inkjet prints8” x 10” 150 5.15 MB

Photo prints4” x 6” 300 6.18 MB5” x 7” 300 9.01 MB8” x 10” 300 20.6 MB

But I don’t know today all the possible uses of my image…

300magic number

5 x 7 @ 300 dpi

Problem with publication

PowerPoint or web image 10” x 7.5” @ 96 dpi 1.98 MB

Publication image 6” x 4” @ 300 dpi 6.18 MB

can’t publish with web images

When resolution is too low

Scaling - doesn't change the number of pixels, just the resolution

Height x width

Dots per inch

File size

4 x 6

300 dpi

6.18 MB

8 x 12

150 dpi

6.18 MB

When resolution is too low

Resampling - changes the number of pixels Downsample - delete pixels; cut file size

Upsample - add pixels; increases file size

upsampling doesn’t add detail = fuzzy

4 x 6

300 dpi

6.18 MB

4 x 6

150 dpi

3 MB

4 x 6

300 dpi

6.18 MB

8 x 10

300 dpi

20 MB

very common

interpolation

If you only learn 1 thing!

Relationship of resolution and image size

BREAK?

Capture devices

Cell phonecamera

Point-n-shoot camera

SLR digitalcamera

Flatbedscanner

Digital videocamera

Garbage in = garbage out

Cell phone Point-n-shoot SLR

Image editing software

Beginner Google Picasa free Adobe Photoshop Album free

Mid-level - home / business use Adobe PhotoShop Elements $100 Corel Paint Shop Pro $100

Advanced - graphics professional Adobe PhotoShop CS3 $650

don’t buy CS3 - invest in a better camera

Demos

Portrait photos Remove red eye / flash

reflections in glasses Too dark - too light Remove date stamp

Landscape photos Straighten horizon line Remove telephone lines

Group photos Diagnostic scans Newspaper clippings

Image correction steps

1. Crop 2. Resize # of pixels3. Adjust highlights and shadows (levels)4. Adjust color balance5. Sharpen filters6. Save as appropriate file format (master)7. Remove blemishes8. Convert to grayscale or CMYK if appropriate9. Save as appropriate file format (output

version)

Crop & resize # of pixels

Crop tool No restriction Aspect ratio > select size (5 x 7 in)

Image > Resize > Image size dialog box Resampling changes # of pixels

Black point White point

Tonal correction

Histogram based on 256 levels of gray Black point (0) White point (255) Mid-range slider

Enhance > Adjust lighting > Levels

Color correction

Color correct by adding or removing color complements

About color management

RGB sRGB CMYK

Over sharpen = halo artifacts and aliasing

Sharpening

Filter > sharpen > unsharp mask Amount = ~ 100% Radius = 1.5 Threshold = 4

Remove blemishes

Eraser Clone Healing brush Red eye removal

corrected

Save - File formats

Applications .jpg .gif .png .pdf .tif .psd

PowerPoint X X X X X

E-mail X X X X

Website X X X

InDesign X X X

PhotoShop X X X X X X

Word X X X X X

Use compression

File formats

.jpg (joint photographic experts group) Compression options 1-12 Good for PowerPoint, web, and email Caution: repeated saves degrades image quality

.tif (tagged-image file format) Most popular, good for transfer Mac to PC Preferred format for publication Retains layers

.psd (PhotoShop document) Retains layers Can only be opened by Photoshop

Save as

Select TIF from format menu

Name the file Select location to

“save as” Click save

For JPEG Select 7 (medium)

Photo printing

Online printing & sharing Kodak Gallery Snapfish Flickr

Print only services Photo kiosks at CVS, Walgreens, Kroger, Biggs

Image catalog/databases

Organization Subcollections Metadata File naming

Database software Storage (with backup!) Long-term expandability

Catalog & storage

Software (image preview, search functions) Picasa iPhoto ACDSee Photo Manager Extensis Portfolio

Storage (with backup!) CD or DVD Hard drive External hard drive Online