ROBUSKEY® Operation Guide

for Adobe® Photoshop® ( Windows Version 3.1 )

May 1, 2011


Table of Contents


What is Operation Guide for

This document describes how to operate ROBUSKEY when you would like to make a Chroma-Key image synthesis.

If it was very first time for you to use ROBUSKEY, please read "Basic Operation and Screen Instruction."

If you would like to know some more, please read "Tips for Taking Photos for ROBUSKEY" and little further.


Basic Operation and Screen Instruction

Here describes ROBUSKEY's screen instruction and basic operation.


Tips for Taking Photos for ROBUSKEY

ROBUSKEY synthesizes specialized to green background image and blue background image, though, there is a range of color suitable to Chroma-Keying. ROBUSKEY performs its best with certain range of background color.

Lighting

ROBUSKEY has a function "Smooth BG" which clears background's uneven, though, ROBUSKEY performs more precisely by irradiate uniformly.

Or, by using the same lighting (orient light etc.) with the background image to be synthesized allows more natural synthesis.

White Balance

ROBUSKEY assumes that processing image's white balance is adjusted properly. Please set the appropriate white balance according to the instructions of your camera.

In particular, removal of reflections in the background to white skin and clothing must have been properly set the white balance.

Background Color Range

Here are the samples of suitable / unsuitable background color:

Green Backgrounds Blue Backgrounds
Most Suitable HSB color system
[ H=100°, S=60%, B=75% ]
HSB color system
[ H=200°, S=60%, B=75% ]
ROBUSKEY performs its best with these background color or similar.
Unsuitable (Saturation)HSB color system
[ S ≤ 40% ]
HSB color system
[ S ≤ 40% ]
Extraction precision will decrease at edges like strand of hair.
Unsuitable (Brightness)HSB color system
[ B ≤ 50% ]
HSB color system
[ B ≤ 65% ]
HSB color system
[ B ≥ 90% ]
HSB color system
[ B ≥ 90% ]
Increased noise will degrade the overall extraction accuracy.
Other Unsuitable Color Some yellow

HSB color system is, expresses color by H(Hue), S(Saturation) and B(Brightness). You can see these values at "information window" of Photoshop. See Photoshop manual for detail.


Tips for Preprocessing Images

Here describes about the points you may want to care about the images you take, prior to open by Photoshop.

RAW Development

When shooting with High-spec camera such as digital SLR, RAW Development is needed prior to Chroma-Keying. In this case, extract precision increases when RAW development is done by development software included with camera, instead of Photoshop's Camera Raw.

ROBUSKEY is tuned for images taken by ordinary commercial camera, such as Canon, Nikon Olympus, Fuji Film etc. Since the characteristics of Photoshop's Camera Raw are very different, the extraction precision may lose depends on subjects. In particular, white color may remain at strand of dark-haired subject.

Color Tuning

Color tuning using tone curve etc, is recommended to use "after" ROBUSKEY processing is done.

ROBUSKEY implements its high quality in accurate detection by precise calculation, based on the relationshop between subject and background colors. When this color-relationship changes, by applying color tuning prior to Chroma-Keying, may cause of the decrease of extraction precision.


Fine Tuning on Image Synthesis

The quality of synthesized image can be tuned by editing parameters. For details of those parameters, see "Parameters Description".

Since ROBUSKEY is specialized to processing small region (such as strand of hair), other parts may take effect which you don't want..

You can solve this kind of problem by splitting image into a few parts by creating mask, apply Chroma-Key to each part with appropriate parameters, and then, shades them.

Example: Green Subject with Green Background

Here is how to Chroma-Key a subject contains green part with green background. Missing part of the color of subject, such as some yellow, can be amended in the same way.

Source Image Result 1 Result 2
Whole Image
Chroma-Keying whole image with ROBUSKEY results as "Result 1"..
Partial Image
You can see her green belt has disappeared.
After Tuning
Copy the original image and paste it into peripheral zone of transparent belt.

Parameters Description

Here describes about how each parameter takes effect to Chroma-Key.

Despill Color Adjustment (Green Background Mode): warm colors(skin, brown hair etc.)

Slides to Left

Amends amount of despill at reddish portion of the subject, such as skin or brown hair.

Slides to Right
Despills more green color reflecting on skin or brown hair. Despills less green color reflecting on skin or brown hair.

Despill Color Adjustment (Green Background Mode): cold colors(blueish clothes etc.)

In contrast to warm colors, amends amount of despill cold colors (such as blueish clothes etc.). Since ROBUSKEY V3.1 has achieved its algorithm, this parameter is little need to adjust.

Despill Color Adjustment (Blue Background Mode): warm colors (skin, brown hair etc.)

Slides to Left When you use blue background, you can amend colors of the skin or brown hair by using this parameter. Slides to Right
Skin and brown hair will be more reddish. Skin and brown hair will be less reddish, becomes blackish.

Despill Color Adjustment (Blue Background Mode): hilight colors (white vail etc.)

Slides to Left Editing warm colors (skin, brown hair) parameter, may take effect to highlight part. In this case, amend colors by editing this parameter. Slides to Right
Highlight parts becomes rather veige/pinkish. Highlight parts becomes more whitish.

Despill Color Adjustment (Blue Background Mode): dark colors( black hair etc.)

Slides to Left Editing warm colors (skin, brown hair) parameter, may take effect to dark color part. In this case, amend colors by editing this parameter. Slides to Right
The dark color part becomes rather brownish. The dark color part becomes more Editing warm colors (skin, brown hair) parameter, may take effect to highlight part. In this case, amend colors by editing this parameter.blackish

Uneven Background Correction and Background Tone Adjustment

Uneven background correction is often used with background tone adjustment, to control the amount of extraction in background area.

Uneven Background Correction: On Uneven Background Correction: Off

Despills shadows made by darkening of the lens or the subject.

You can also utilizing the shadow of the subject..

Background Tone Adjustment(Left)

You can leave detailed outlines, such as strand of hair, while the amount of extraction decreases at dark part of the background.

Background Tone Adjustment(Right)

You can leave more amount of extraction at dark part of the background, while detailed outlines, such as strand of hair are lost.


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