Chapter 2 Specifying the Scanner Settings

Preparing Gamma Curve Data

Gamma curve data consists of a 258-line text file (*.gmm) containing the output values for the 256 levels of input values.

Always enter a connect as the first line of the gamma curve data and “256” in the second line to indicate the number of data items.

Lines 3 onwards set the output values for each input value, starting with the output values for “0” in line 3, “1” in line 4 and so on through to the output value for input value “255” in line 258.

Smaller values in the gamma curve data give a darker image while larger values produce a lighter image.

Example of Prepared Gamma Curve Data

Normally, the gamma curve leans to the right. However, the leftward-leaning gamma curve shown in the lower figure below inverts all the output values so that the result- ing image is also inverted.

Gamma curve data

 

1st line

: gamma curve

255

2nd line

: 256

 

3rd line

: 0

 

4th line

: 1

 

5th line

: 2

Output value

 

 

 

 

 

 

 

 

 

253rd line : 250

 

254th line : 251

 

255th line : 252

 

256th line : 253

0

257th line : 254

 

258th line : 255

 

Gamma curve data (inverted)

 

 

1st line

: inverted linear gamma curve

 

2nd line

: 256

255

 

3rd line

: 255

 

 

4th line

: 254

 

 

5th line

: 253

 

 

 

 

Output value

 

253rd line : 5

 

 

254th line : 4

 

 

255th line : 3

 

 

256th line : 2

 

 

257th line : 1

0

 

258th line : 0

 

(Gamma curve)

255

Input value

(Gamma curve)

255

Input value

32

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Canon 800II manual Preparing Gamma Curve Data

800II specifications

The Canon 800 II is a remarkable addition to Canon's lineup of high-performance telephoto lenses, specifically designed for professional photographers and wildlife enthusiasts. Its impressive features, advanced technologies, and robust characteristics make it a popular choice for capturing exceptional images even in challenging conditions.

At the core of the Canon 800 II is its focal length of 800mm, which allows photographers to achieve stunning close-ups from considerable distances. This is particularly beneficial for wildlife and sports photography, where getting close to the subject may not be feasible. The lens has a fast f/5.6 aperture, enabling excellent performance in low-light environments while maintaining a shallow depth of field for beautifully blurred backgrounds.

One of the standout features of the Canon 800 II is its lightweight design made possible by the incorporation of advanced materials such as magnesium alloy and fluorite elements. Weighing significantly less than its predecessor, the lens is easier to handle during long shooting sessions and provides superb portability for photographers on the move.

Image stabilization technology is another impressive aspect of the Canon 800 II. With a sophisticated image stabilization system, photographers can achieve steady shots even at slower shutter speeds, reducing the potential for camera shake. This feature is particularly useful when shooting handheld or in challenging lighting conditions.

The lens also incorporates Canon’s Super Spectra Coating, which helps to minimize ghosting and flare while enhancing contrast and color accuracy. This ensures that images are sharp and vibrant, making it easier to capture the intricate details of distant subjects.

Autofocus on the Canon 800 II is powered by a ring-type ultrasonic motor (USM), allowing for fast and silent focusing. This is essential for capturing fleeting moments in wildlife photography, where speed and accuracy are crucial. Additionally, the lens features full-time manual focus, providing photographers with the ability to fine-tune their focus without having to switch modes.

Durability is key for professional-grade lenses, and the Canon 800 II is designed to withstand tough environmental conditions. With a weather-sealed construction, it offers protection against moisture and dust, allowing photographers to work confidently in various climates.

Overall, the Canon 800 II stands out for its exceptional performance, lightweight design, advanced image stabilization, and robust build quality. Whether photographing wildlife, sports, or scenic landscapes, this lens offers unrivaled capabilities that help professionals capture stunning images with ease and precision.