Camera Oscura

Highlight areas of the image that may exhibit luminance or gamut clipping.

When an image is sent to a display device, each pixel is normally represented as a set of 3 numbers, representing the intensity of the red, green and blue primary colors in the output color space. Because the output color space is usually closely related to hardware with physical limations, there is a maximum permitted value for the [R,G,B] channels, representing the maximum available intensity for that color space. Similarly, there is also a minimum value below which pixel values will be mapped to zero. When we try to convert from a larger color space to the final output color space, any values exceeding this maximum will be clamped to the maximum value, and any values below the minimum will be clamped to zero. This process is called “clipping” and it will lead to lost detail, or “incorrect” colors for any pixels with clipped channels.

View and modify the history stack of the current darkroom image.

This module lists every change of state (activate/de-activate/move/change parameters) for all processing modules that have been modified for the current image. Select a point in the stack to return to that point in the development history of the image. Shift+click an item in the history stack to expand that module in the right-hand module panel without changing the current edit.

Highlight areas of the image that may exhibit gamut clipping.

Click the

Right-click on the icon to open a dialog with configuration parameters – these are the same as for the soft proof option.

You might also like to consider using the clipping warning, which also provides under- and over-exposure warnings as well as a gamut check similar to that offered by this module.

View and create multiple versions of the current image. Each version can be edited independently without affecting other versions – all versions use the same underlying image file, but the editing history of each version is stored in its own independent XMP sidecar file.

The duplicate manager lists each version of the current darkroom image along with its preview thumbnail. Hold down the left mouse button on a thumbnail to temporarily show that version in the center view. Double-click to switch to that version and edit it.

Manage all masks and shapes for the current image.

This module can be used to create, rename, edit and delete shapes. You can add shapes to and remove shapes from a mask, group shapes together, and combine them using set operators.

The top line of the mask manager panel contains buttons that can be used to create new shapes. These are the same as in the drawn mask interface of in processing modules.

Take color samples from the current darkroom image, display their values in multiple ways and compare colors from different locations.

The color picker is activated by pressing the color picker icon. The module’s parameters will remain in effect until you leave the darkroom mode.

Besides the global color picker described here, many Ansel modules (e.g. RGB curve) also contain local color pickers which are used to set individual module parameters. You should be aware that these two forms of color picker do not always work in the same color space. The global color picker works in the histogram color space and takes its samples after the complete pixelpipe has been processed. Local color pickers run in the color space of the module in which they are activated and reflect the input or output data of that module within the pixelpipe.

A number of commonly-used compositional guides can be overlaid on your image while you are editing. These can be enabled either globally (all the time) or locally (when certain modules are active).

Other darkroom functionality also draws colored overlay lines on the image (for example, drawn masks). An option is also provided to change the color of those overlays (see below).

Guide globali

Left-click the

icon in the bottom bar to globally display guide overlays. The overlays will remain switched on until you click the button a second time to switch them off.

Display information about the current image in a darkroom panel.

The contents of this line can be set in preferences > darkroom. See the variables section for information about the variables that can be used here. You can also insert a newline with $(NL).

The image information line can be displayed in the top, bottom, left or right panel depending on an additional configuration item in preferences > darkroom.

Store development snapshots and compare with the current edit.

A snapshot is a stored bitmap of the center image in the darkroom view. Snapshots can be taken at any point in the development process and later overlaid onto the current center view. This allows you to undertake a side by side comparison (by default left=snapshot, right=active edit) while you are tuning parameters of a module. This can also be combined with the history stack module to compare a snapshot against different stages of development.

Zoom and pan the current image.

On the top left hand side of the darkroom, the navigation panel displays a full preview of the current image with a rectangle showing the area that is currently visible in the central panel. Drag the rectangle around to pan the zoomed-in view. The current zoom scale is displayed to the right of the preview image. Click on that figure for a quick access to some common zoom levels.

Change the order of the processing modules in the darkroom using presets.

When processing an image, the active modules are applied in a specific order, which is shown in the right-hand panel of the darkroom view. This module provides information about the current ordering of the processing modules in the pixelpipe. The name of the currently-selected preset is shown in the module header (or “custom” if the user has manually modified the order). The following presets are available for selection.

View your image rendered using a selected color profile.

Click the

Highlight areas of the image where color channels of the raw input file are clipped.

Clipped color channels imply an overexposed image with loss of information in the affected areas. Some of this information may be recoverable using the highlight reconstruction, color reconstruction or filmic rgb modules.

Click on the

Assess colors and brightness in your image using ISO 12646:2008 recommended viewing conditions.

When developing an image, the way we perceive brightness, contrast and saturation is influenced by the surrounding ambient conditions. If an image is displayed against a dark background, this can have a number of adverse effects on our perception of that image:

• Exaggeration of the perceived exposure makes the image seems brighter than it really is. This is nicely illustrated by the Adelson checkerboard shadow effect .
• A decrease in the perceived saturation in the image makes the colors seem less rich than they really are (the Hunt effect).
• A decrease in the perceived contrast in the image makes the tones seem flatter than they really are (Bartleson-Breneman effect 3)

The end result is that the final image can end up being too dark and overly-processed in terms of contrast and color saturation. To avoid this, the “ISO 12646:2008” standard makes some recommendations about the conditions under which the colors of an image should be assessed. The color assessment module in the darkroom places a frame around the image to help the user better assess the colors in the image, along the lines of those recommendations.