ComfyUI Node: Gear · Color Grade (exr-viewer)

Gear · Color Grade (exr-viewer):

The GearColorGrade node is a powerful tool designed for color grading high dynamic range (HDR) images, specifically tailored for AI artists working with scene-linear HDR content. This node leverages an exr-viewer-style grading pipeline, allowing you to apply sophisticated color adjustments to your images. It provides a user-friendly interface with a modal containing color wheels, scopes, and a wipe compare feature, enabling precise control over the visual output. The node is particularly beneficial for those looking to enhance their images with professional-grade color grading techniques, offering a range of adjustments such as exposure, tone mapping, temperature, and more. By integrating this node into your workflow, you can achieve visually stunning results that adhere to industry standards.

Gear · Color Grade (exr-viewer) Input Parameters:

hdr_linear

This parameter represents the scene-linear HDR image that you wish to grade. It is the primary input for the node and typically comes from the hdr_linear output of the Gear LogC3 Decode node. The values in this image can exceed 1.0, allowing for a wide range of luminance levels to be processed.

exposure

The exposure parameter adjusts the overall brightness of the image. It ranges from -10.0 to 10.0, with a default value of 0.0. Increasing the exposure brightens the image, while decreasing it darkens the image, allowing you to fine-tune the image's luminance.

tone_map

This parameter allows you to select a tone mapping algorithm to apply to the image. Options include "None", "Reinhard", "ACES Fitted", "AgX", and "Hable", with "ACES Fitted" as the default. Tone mapping is crucial for converting HDR images to display-referred formats, ensuring that details are preserved in both highlights and shadows.

soft_clip

Soft clip controls the compression of highlights to prevent clipping. It ranges from 0.0 to 1.0, with a default of 0.0. A higher value results in smoother transitions in bright areas, preserving detail and preventing harsh cutoffs.

temperature

This parameter adjusts the color temperature of the image, ranging from -1.0 to 1.0, with a default of 0.0. It allows you to make the image appear warmer or cooler, simulating changes in lighting conditions.

tint

Tint adjusts the green-magenta balance of the image, with a range from -1.0 to 1.0 and a default of 0.0. This is useful for correcting color casts and achieving a more natural look.

lift_r, lift_g, lift_b

These parameters control the lift, or shadow adjustment, for the red, green, and blue channels individually. Each ranges from -1.0 to 1.0, with a default of 0.0. Adjusting these values can help balance the shadows and correct color imbalances.

gamma_r, gamma_g, gamma_b

Gamma adjustments for the red, green, and blue channels, respectively, with each ranging from 0.1 to 4.0 and a default of 1.0. These parameters affect the midtones of the image, allowing for precise control over contrast and brightness.

gain_r, gain_g, gain_b

These parameters adjust the gain, or highlight intensity, for the red, green, and blue channels. Each ranges from 0.0 to 4.0, with a default of 1.0. Gain adjustments are useful for enhancing the brightness of highlights without affecting shadows.

offset_r, offset_g, offset_b

Offset parameters for the red, green, and blue channels, each ranging from -1.0 to 1.0 with a default of 0.0. These parameters shift the entire tonal range of the image, useful for correcting exposure and color balance.

contrast

This parameter adjusts the contrast of the image, ranging from 0.0 to 4.0, with a default of 1.0. Increasing contrast makes the darks darker and the lights lighter, enhancing the overall dynamic range.

pivot

The pivot parameter sets the point around which contrast adjustments are made, ranging from 0.001 to 1.0, with a default of 0.18. This allows for more precise control over which tonal range is affected by contrast changes.

shadows

Shadows adjustment ranges from -2.0 to 2.0, with a default of 0.0. It specifically targets the darker areas of the image, allowing you to lift or deepen shadows without affecting highlights.

highlights

This parameter adjusts the highlights of the image, ranging from -2.0 to 2.0, with a default of 0.0. It allows you to recover details in bright areas or enhance them for a more dramatic effect.

saturation

Saturation controls the intensity of colors in the image, ranging from 0.0 to 3.0, with a default of 1.0. Increasing saturation makes colors more vivid, while decreasing it results in a more muted look.

vibrance

Vibrance adjusts the intensity of less saturated colors, ranging from -2.0 to 2.0, with a default of 0.0. It is useful for enhancing colors without oversaturating already vibrant areas.

hue_shift

This parameter shifts the overall hue of the image, ranging from -180.0 to 180.0, with a default of 0.0. It allows for creative color adjustments and corrections.

false_color

A boolean parameter that, when enabled, applies a false color effect to the image. This is useful for visualizing luminance levels and ensuring proper exposure.

sdr_reference

An optional input that provides a display-referred SDR image for A|B wipe comparison in the grading panel. This helps in evaluating the graded HDR image against a standard reference.

Gear · Color Grade (exr-viewer) Output Parameters:

graded_display

The graded_display output is a display-referred sRGB image that has undergone tone mapping and an opto-electronic transfer function (OETF). It is clamped between 0 and 1, making it suitable for viewing on standard displays. This output reflects the final graded appearance of the image.

graded_linear

The graded_linear output is the scene-linear HDR image after grading but before tone mapping. It retains the full dynamic range of the original HDR content, allowing for further adjustments or use in HDR workflows.

Gear · Color Grade (exr-viewer) Usage Tips:

• Utilize the tone_map parameter to experiment with different tone mapping algorithms and find the one that best suits your image's aesthetic.
• Adjust the exposure and contrast parameters to achieve the desired brightness and dynamic range, ensuring that details are preserved in both shadows and highlights.
• Use the lift, gamma, and gain parameters to fine-tune the color balance and contrast of individual color channels, correcting any color casts or imbalances.
• Leverage the vibrance parameter to enhance colors in a subtle way, avoiding oversaturation of already vivid areas.
• Take advantage of the false_color option to visualize luminance levels and ensure that your image is properly exposed.

Gear · Color Grade (exr-viewer) Common Errors and Solutions:

"Input image is not HDR"

• Explanation: This error occurs when the input image does not have the expected HDR format or values exceeding 1.0.
• Solution: Ensure that the input image is a scene-linear HDR image, typically obtained from the hdr_linear output of the Gear LogC3 Decode node.

"Tone map selection invalid"

• Explanation: This error indicates that the selected tone mapping option is not recognized by the node.
• Solution: Verify that the tone_map parameter is set to one of the valid options: "None", "Reinhard", "ACES Fitted", "AgX", or "Hable".

"Parameter out of range"

• Explanation: This error occurs when one or more input parameters are set outside their allowed range.
• Solution: Check all input parameters and ensure they are within the specified minimum and maximum values. Adjust any parameters that are out of range.