COURSE NAVIGATION

Image Enhancement

This is what Claro is all about! A few points before you read on:

  • The sliders represent target levels, not actions! Image enhancement is dynamic, image specific, and based on image analysis.
  • The sliders middle position, with a corresponding value of 0, means that it is on our default setting. 0 does NOT mean that there won’t be a correction. To disable a function completely, uncheck the checkbox that corresponds to the setting.
  • See also “Best practices to tune enhancement settings” 
image-enhancement
 Sharpness

Sets the target level of sharpness. Depending on individual characteristics of the original image like level of sharpness, number of pixels, noise etc, the actual unsharp mask properties like radius, threshold and amount are defined.

Brightness

Sets the target level of brightness. The actual brightness correction depends also on the characteristics of images. Images shot at night versus images of winter-sports will not be corrected to the same brightness level.

Contrast

Sets the target level of contrast.

Saturation

Sets the target level of saturation.

Set black & white point

Sets the black and/or white point in the image. In advanced settings are more settings available to tune the behaviour of this feature.

Apply noise filter on noisy images

Noise filtering based on noise analysis.

Apply local contrast for shadows

This feature opens up the shadow areas in images.

Apply local contrast for highlights

This feature improves contrast in mid-tones and highlights and preserves details in highlights. The option “Exclude skin tones” is there to avoid too much contrast in skin tones that could emphasise imperfections in skin. In news print, this additional contrast provides for more “depth” in faces and is usually welcome. For higher quality print, the “Exclude skin tones” function is advisable.

Color balance

Removes color casts in images.

Suppress JPEG artefacts

Reduce JPG artefacts in images.

enhancement - advanced settings

Advanced Image Enhancement settings

Black point percentage

This feature influences the effect of setting the black point. Default setting is 100%.

100%: If Claro finds a black point with an RGB value of 10, that point will be set to 0 (black) and the rest of the histogram will be adjusted accordingly.

50%: if Claro finds a black point with an RGB value of 10, that point will be set to 5 (50% of the correction) and the rest of the histogram will be adjusted accordingly.

Note: If Claro finds a black point of 0 (already black), no correction is needed. In that case it does not make a difference what percentage is used here. Therefore, this feature is not meant to set a minimum value for black. That requirement can be met in several ways: with the output ICC profile, with curves (OUTPUT CONVERSION) and with Black limit.

White point percentage

This feature influences the effect of setting the white point. Default setting is 100%.

100%: If Claro finds a white point with an RGB value of 245, that point will be set to 255 (white) and the rest of the histogram will be adjusted accordingly.

50%: if Claro finds a white point with an RGB value of 245, that point will be set to 250 (50% of the correction) and the rest of the histogram will be adjusted accordingly.

Note: If Claro finds a white point of 255 (already white), no correction is needed. In that case it does not make a difference what percentage is used here. Therefore, this feature is not meant to set a maximum value for white. That requirement can be met in several ways: with the output ICC profile, with curves (OUTPUT CONVERSION) and with White limit.

Black point clipping

In setting the black point, a certain percentage of pixels must be “clipped”. Due to electronic noise present in any image, there will always be a black pixel (RGB value 0). Yet we want to find the “real” black point, and ignore noise. The default clipping percentage is 0.1%. This an accepted standard that is also used in Photoshop for example. To increase contrast or find a “real” black point in noisy images, this value should be increased. Typically the range of acceptable settings is between 0.1 and 0.5, but it really depends on the quality of the originals.

White point clipping

In setting the white point, a certain percentage of pixels must be “clipped”. Due to electronic noise present in any image, there will always be a white pixel (RGB value 255). Yet we want to find the “real” white point, and ignore noise. (and maybe also highlights as light-points or solar reflections). The default clipping percentage is 0.1%. This an accepted standard that is also used in Photoshop for example. To increase contrast or find a “real” white point in noisy images, this value should be increased. Typically the range of acceptable settings is between 0.1 and 0.5, but it really depends on the quality of the originals.

Black limit

In print applications, it may be a requirement to have a minimum dot in white areas, and a maximum for black. Achieving this is primarily a function of the output icc profile. However, to avoid spreading the information of the histogram between absolute white and absolute black just to partially reverse that with the output profile, Claro allows to use a black limit and white limit in setting the black and white point. Note that this works in RGB values, therefore 0 is black, 255 is white.

Apply noise filtering in luminosity mode

Convert the image to LAB colorspace and apply noise filtering only on the L (luminance) channel. Colors remain untouched and banding is avoided. However, the net effect of the noise filter is also reduced.

Apply contrast in luminosity mode

Convert the image to LAB colorspace and apply the contrast curve only on the L (luminance) channel. This avoids the increase in saturation otherwise seen if contrast curves are applied on RGB channels.

Apply brightness only for mid tones

By default, if a brightness correction is required, a gamma curve is being used to apply the correction. A gamma curve is stronger in dark areas, and then flattens towards the brighter areas. This is also the default brightness correction curve in for instance Photoshop. By enabling this option, a more bell-shaped curve is used that applies strongest in de mid tones.

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ELPICAL

JOHN DE JONG

Phone +31 (0) 313 633 156
E-Mail [email protected]
Skype ELPICALJOHN
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