ComfyUI Node: ◎ Radiance HDR Expand Dynamic Range

◎ Radiance HDR Expand Dynamic Range:

The HDRExpandDynamicRange node is designed to transform Standard Dynamic Range (SDR) images into High Dynamic Range (HDR) images by recovering highlights and extending the exposure latitude. This process enhances the visual quality of images by increasing the range of luminance levels, allowing for more detail in both the shadows and highlights. The node is particularly useful for AI artists looking to improve the dynamic range of their images, making them appear more vibrant and realistic. By expanding the dynamic range, this node helps in achieving a more natural look, especially in scenes with high contrast, such as bright skies or dimly lit interiors.

◎ Radiance HDR Expand Dynamic Range Input Parameters:

image

This parameter represents the input image that you want to expand from SDR to HDR. It is crucial as it serves as the base for all subsequent processing. The image should be in a format that supports HDR processing, typically a tensor format, to ensure compatibility with the node's operations.

source_gamma

The source_gamma parameter defines the gamma correction applied to the input image. It adjusts the luminance of the image to match the display characteristics. The default value is 2.2, with a range from 1.0 to 3.0. Adjusting this value can help in achieving the desired brightness and contrast in the final HDR image.

highlight_recovery

This parameter controls the extent to which highlights are recovered in the image. With a default value of 1.0 and a range from 0.0 to 2.0, it allows you to fine-tune the recovery of details in overexposed areas, ensuring that bright regions retain their texture and detail.

black_point

The black_point parameter sets the level at which shadows are clipped. It ranges from -0.1 to 0.1, with a default of 0.0. Adjusting this value can help in preserving shadow details or enhancing contrast by deepening the blacks in the image.

target_stops

This parameter specifies the target number of stops for the expanded dynamic range, with a default of 14.0 and a range from 8.0 to 20.0. It determines the overall exposure latitude of the HDR image, affecting how much detail is visible in both the darkest and brightest parts of the image.

highlight_rolloff

The highlight_rolloff parameter controls the smoothness of the transition from midtones to highlights. It ranges from 1.0 to 3.0, with a default of 1.5. This parameter helps in preventing harsh transitions and maintaining a natural look in the bright areas of the image.

◎ Radiance HDR Expand Dynamic Range Output Parameters:

image

The output parameter is the processed image, now expanded to HDR dynamic range. This image will have enhanced detail in both shadows and highlights, providing a more realistic and visually appealing result. The output is typically in a tensor format, ready for further processing or display.

◎ Radiance HDR Expand Dynamic Range Usage Tips:

• To achieve the best results, start with a well-exposed SDR image and adjust the source_gamma to match the characteristics of your display device.
• Use the highlight_recovery parameter to bring back details in overexposed areas, especially useful for images with bright skies or reflective surfaces.
• Experiment with the target_stops to find the right balance between shadow and highlight detail, depending on the specific lighting conditions of your image.

◎ Radiance HDR Expand Dynamic Range Common Errors and Solutions:

Image format not supported

• Explanation: The input image is not in a compatible format for HDR processing.
• Solution: Ensure that the input image is in a tensor format that supports HDR operations.

Invalid gamma value

• Explanation: The source_gamma value is outside the acceptable range.
• Solution: Adjust the source_gamma parameter to be within the range of 1.0 to 3.0.

Highlight recovery ineffective

• Explanation: The highlight_recovery parameter is set too low, resulting in insufficient detail recovery in bright areas.
• Solution: Increase the highlight_recovery value to enhance detail recovery in overexposed regions.