Visit Red River Paper!
Digital PhotoCorner

Digital Photo Corner
Home

About This Site
Site Help & Hints

DIGIPHOTO 101
SPONSORED BY
Red River Paper
Visit The Class
Click Here

CRUISE PHOTOS
2007, 2008, Other

Digital Photography Cruise

ALL ABOUT
Monitor Calibration
Resolution
Digital Photography
Digital Terms
Easy Digital Imaging

DIGITAL PROS
New American Pin-ups
Al Francekevich
Hiroshi Kamakura
Renata Ratajczyk

Digital Camera Magazine

INFO-SHARE
Ask & You'll Receive

Maya Powerex batteries

HOW TO DO IT
Print Like A Pro
Emailing Photos
Open Shade Portraits
Shoot A Picture Essay
Using Photo CD

DIGITAL TOOLS
Nifty New Goodies
You Just Gotta Have

Great New Books

TECH TOPICS
Using Old Lenses
Recognizing Digital Artifacts

Visit Dealtime!

FREE STUFF
Model Releases

CLASSIFIED ADS
Buy, Sell, Trade Here!

RESOURCES
Stock Photography
Great New Books!
Other DigiPhoto Sites

EXHIBIT HALLS
Digital Photography
DP101 Student Gallery

E-mail
How To Send Us
Email & Photos

THE ARCHIVES
It's Here...Somewhere

Our Privacy Policy


Digital Artifacts…

Blooming

Blooming or light spill over, is a problem caused by photons spilling from one sensor element to another creating what can be a whole region of over fill, resulting in highlight blow out and / or weird color in these areas. Larger sensor elements can collect and contain the photons better than the smaller ones found in most of today's consumer level digital cameras. CMOS sensors which have some drawbacks are actually better in this regard. If this effect bothers you, it's best to avoid subject matter with bright reflections.

Pixelation

When a relatively small sensor array is used to create an image, pixelation becomes very apparent. Larger sensor arrays are more expensive but supply enough information to produce a more lifelike picture. Pixelation is most noticeable as stairways on diagonal lines that are jagged instead of straight and smooth. On type this effect is sometimes called the "jaggies" but it's essentially the same problem in photo imaging.

Interpolation

artLips
The lipstick is red and the highlights are white, but they display an effect known as "Christmas tree lights" due to the color filter mosaic over the sensor array.

A variation on this theme is "Christmas tree lights" or color aliasing artifacts which are a function of the way that color filtration is laid down on the sensor and is particularly apparent when an image is greatly enlarged. On many sensors Red (R), Green (G) and Blue (B) filtration is applied as RGBGRGBGR...with twice as many green pixels as red and blue. This is because human vision, which we want to emulate, is most sensitive to the green wavelengths, and also because the CCD uses the green reading to compute luminance. The resulting pattern, blown up, particularly on diagonal lines is an unreal mosaic of colors that are a result of averaging between adjacent pixels. A less than perfect work-around for this problem is to desaturate the color in specific areas on an image where fringing is apparent.

There are many different ways to expand an image's size. Some well known examples are the Linear, Bilinear and Bicubic methods which can be chosen in Adobe Photoshop's Preferences, and another from Live Picture which is a mixture of concatenation and pixel decimation. In the Photoshop methods, the basic tradeoff is between speed and quality, but while Bicubic interpolation is widely regarded as the best method, it may not always give the most pleasing results.

If you are experiencing "ghosting" on diagonal lines, for instance, it may be better to change your software's preferences, and try Bilinear instead. The Live Picture concatenation algorithms which work so well on continuous tone image sections, fall down somewhat on hard edged lines, particularly when the lines are not exactly vertical or horizontal. Camera manufacturers create their own interpolation systems specific for the task, and secret unto themselves. Unfortunately if you don't like their interpolation regime, you're stuck with it.

 

Go to previous page Page 2 of  5 Go to next page


Lensbabies.com Digital PhotoCorner

1998-2013 Arthur Bleich. All rights reserved.