Aumente o disminuya el brillo general de una imagen.

Este módulo tiene dos modos de funcionamiento:

manual
Configure la exposición, el nivel de negro y el umbral de recorte manualmente
automático (solo imágenes RAW)
Utilice un análisis del histograma de la imagen para establecer automáticamente la exposición. Ansel selecciona automáticamente la compensación de exposición que se requiere para cambiar el percentil seleccionado al nivel objetivo seleccionado (consulte las definiciones a continuación). Este modo es particularmente útil para alterar automáticamente una gran cantidad de imágenes para que tengan la misma exposición. Un caso de uso típico del modo automático es el deslumbramiento de fotografías de time-lapse.

controles del módulo

modo
Elija el modo de funcionamiento (automático / manual).
compensar la exposición de la cámara (modo manual)
Elimina automáticamente el sesgo de exposición de la cámara (tomado de los datos Exif de la imagen).
exposure (manual mode)
Increase (move to the right) or decrease (move to the left) the exposure value (EV). To adjust by more than the default limits shown on the slider, right click and enter the desired value up to +/-18 EV (see module controls).
The color picker tool on the right sets the exposure such that the average of the selected region matches the target lightness defined in spot exposure mapping options.
umbral de recorte (modo manual)
Defina qué porcentaje de valores de brillo se recortarán en el cálculo de la exposición y la corrección del nivel de negro. Utilice el selector de color para tomar una muestra de una parte de la imagen que se utilizará para este cálculo.
percentil (modo automático)
Defina una ubicación en el histograma que se utilizará para la corrección automática de la exposición. Un percentil del 50% denota una posición en el histograma donde el 50% de los valores de píxeles están por encima y el 50% de los valores de píxeles están por debajo de esa exposición.
nivel objetivo (modo automático)
Defina el nivel objetivo para la corrección de exposición automática (EV) en relación con el punto blanco de la cámara.
corrección del nivel de negro (modos manual y automático)
Ajuste el punto de nivel de negro para eliminar los valores RGB negativos.

Note: Do not use the black level correction to add more density in blacks as this can clip near-black colors out of gamut by generating negative RGB values. This can cause problems with some modules later in the pixelpipe. Instead, use a tone mapping curve to add density to the blacks. For example, you can use the relative black exposure slider on the scene tab of the filmic rgb module.

spot exposure mapping

The spot mapping feature is designed to help with batch-editing a series of images in an efficient way. In this scenario, you typically develop a single reference image for the whole batch and then copy&paste the development stack to all of the other images in the batch.

Unfortunately, the light often changes slightly between shots, even within the same series captured in the same conditions. This can be the result of a cloud passing by the sun in natural light, surface reflections having less “shine” from a different angle, or simply due to unavoidable variability in the mechanical diaphragm aperture. Each image will still need some individual fine-tuning if you want a perfectly even look over the whole series, and this can be both time-consuming and frustrating.

Spot exposure mapping allows you to define a target brightness, in terms of exposure, for a particular region of the image (the control sample), which you then match against the same target brightness in other images. The control sample can either be a critical part of your subject that needs to have constant brightness, or a non-moving and consistently-lit surface over your series of images.

The mapping process consists of two steps.

paso 1: aplica el blanco

There are two ways of setting the target brightness for your control sample:

  1. if you know or expect an arbitrary lightness for the control sample (for example, a gray card, a color chart, a product or a logo of a specified brightness), you can set its L value directly, in CIE Lab 1976 space,
  2. if you simply want to match the development of your reference image, set the spot mode to measure, then enable the color picker (to the right of the exposure slider) and draw a rectangle over your control sample. The input column will then be updated with the lightness value of the control sample before the exposure correction, and the target column will show the resulting lightness of the control sample after the current exposure setting is applied.

If you reset the lightness value, the default value is 50% (middle-gray) – this can be useful to quickly set the average exposure of any image.

Note that the target value is not reset when you reset the module itself, but is stored indefinitely in Ansel’s configuration and will be available on next launch as well as for the next image you develop.

step 2 : match the target

When you open a new image, the spot mode is automatically reset to correction. Using the color picker attached to the exposure slider, you can then directly reselect your control sample in the new image. The proper exposure setting required for the control sample to match the memorized target lightness will be automatically computed, and the setting will be updated in the same operation.

Esta operación puede ser repetida tantas veces según las imágenes que tiene en su serie sin más trabajo.

Note 1: Trying to match lightness of moving parts of a subject across frames can prove tricky because they can have legitimate changes in their illumination as their orientation changes with respect to the main light source. For example, a part of the face can be fully lit in some frames and partially shaded in others. An inconsistently-lit control sample will generally not provide a robust reference for lightness matching across a series and may result in more work than manually matching it with visual feedback.

Note 2: The exposure module works (by default) in the scene-referred, linear, camera RGB part of the pixel pipeline, before the input color profile is applied. However, the conversion from camera RGB to CIE Lab 1976 space relies on the input color profile. All of the lightness L metrics given in the spot mapping settings will use the input profile defined later in the input color profile module to perform the conversion accurately, but the conversion itself assumes a linear (RAW) signal and will not work for JPEG and PNG images (which are non-linearly encoded before the input color profile module). If you want to use this feature on non-RAW images, you will need to move the exposure module to after input color profile or to use the module order preset v3.0 for JPEG/non-RAW input.

Note 3: Perfectly matching your control sample against the target lightness may still not yield a similar perceptual result, even if the numbers are exactly the same. For example, if your subject sits in front of a background made of some bright parts and some dark parts, the ratio of bright areas / dark areas will affect the perception of contrast and brightness. If this ratio changes across your series, the subject brightness will not appear constant even though the lightness value is exactly constant. For more details, see the checker shadow illusion  and the Chubb illusion .