3.4

Chapter 15 An Overview of Image Adjustments 292
Using the Moire Controls
Digital images often have color artifacts that appear around edges and lines because of
noise created by digital image sensors. Images whose subjects have linear patterns often
introduce a moire pattern that gives the subject a wrinkled or rainbow-colored appearance.
In addition, cameras with image sensors employing Bayer patterns often introduce noise into
monochromatic images. The Moire adjustment controls in the RAW Fine Tuning area of the
Adjustments inspector or the Adjustments pane of the Inspector HUD identify these patterns
and correct these artifacts.
Because many digital cameras have weak anti-aliasing lters, the Moire and Radius parameters
are specically used to correct aliasing in an image caused by edges with high color contrast.
Weak anti-aliasing lters tend to curve edges, skewing the colors in the process. During the RAW
decoding process, OS X scans for high-frequency information in the RAW le, looking for blended
colors, and then replaces the blended colors with the edge colors that originally existed in the
scene. The Moire parameter adjusts the amount of signal to apply the adjustment to. The Radius
parameter adjusts the pixel area (visual threshold) the adjustment is applied to.
Note: The Moire controls replace the Chroma Blur controls found in previous versions
of Aperture.
To adjust the amount of moire reduction applied during the RAW decoding process
1 Select a RAW image.
Note: If the RAW Fine Tuning controls do not appear in the Adjustments inspector or the
Adjustments pane of the Inspector HUD, the selected image is from a previous version of
Aperture. You must rst reprocess the image using the most current RAW image processing. For
more information, see An Overview of Reprocessing Photos on page 76.
2 Adjust the amount of signal to apply the Moire adjustment to using the Moire slider and
value slider.
Use the Moire slider and value
slider to adjust the amount of
signal the Moire adjustment
is applied to during the RAW
decoding process.
A value of 0.00 applies no moire correction during the RAW decoding process. A value greater
than 0.00 applies moire correction during the RAW decoding process.