ComfyUI Node: Gear · LogC3 Decode + Save EXR

Gear · LogC3 Decode + Save EXR:

The GearLogC3DecodeSaveEXR node is designed to facilitate the conversion and storage of high dynamic range (HDR) images encoded in the LogC3 format into a more accessible scene-linear HDR format. This node is particularly beneficial for AI artists working with HDR content, as it not only decodes the LogC3 images but also saves them in the widely-used EXR format, which is ideal for high-fidelity image processing and storage. The node leverages advanced mathematical transformations to ensure that the HDR data is accurately represented in a linear format, making it suitable for further processing or grading. Additionally, it provides a tonemapped preview of the HDR content, allowing users to visualize the results in a more standard dynamic range, which is crucial for making informed adjustments and decisions during the creative process. By automating the conversion and saving process, this node streamlines workflows and ensures that HDR images are preserved with high precision and quality.

Gear · LogC3 Decode + Save EXR Input Parameters:

image

This parameter represents the HDR image input that is encoded in the LogC3 format. It is crucial for the node's operation as it serves as the source data that will be decoded and processed. The image should be in the range of [0,1], which is typical for LogC3 encoded images.

filename_prefix

This string parameter allows you to specify a prefix for the filenames of the saved EXR files. It supports various tokens such as %year%, %month%, %day%, %hour%, %minute%, %second%, and %batch_num%, which are automatically replaced with the corresponding values. This feature ensures that each saved file has a unique name, preventing overwriting. The default value is gear_hdr/%year%%month%%day%_%hour%%minute%%second%.

preview_ev

This float parameter controls the exposure value for the tonemapped preview. It allows you to adjust the brightness of the preview image to better match your desired visualization. The parameter accepts values ranging from -8.0 to 8.0, with a default value of 0.0, and can be adjusted in increments of 0.5.

save_exr

This boolean parameter determines whether the decoded HDR images should be saved as EXR files. When set to True, the node will save the images in the specified output directory. The default value is True, enabling automatic saving of EXR files unless explicitly disabled.

Gear · LogC3 Decode + Save EXR Output Parameters:

hdr_linear

This output provides the scene-linear HDR image, which is the result of decoding the LogC3 input. The values in this image can exceed 1.0, making it suitable for further processing or grading in HDR workflows. This output is essential for maintaining the high dynamic range of the original content.

tonemapped_preview

This output offers a tonemapped version of the HDR image, adjusted according to the specified preview_ev value. It is designed for display in standard dynamic range, allowing you to visualize the HDR content in a more familiar format. This preview is particularly useful for assessing the image's appearance and making creative decisions.

exr_paths

This output is a string containing the newline-joined absolute paths of the saved EXR files. If save_exr is set to False, this output will be an empty string. The paths provided here are crucial for locating the saved files on your system and integrating them into your workflow.

Gear · LogC3 Decode + Save EXR Usage Tips:

• Ensure that your input image is correctly encoded in the LogC3 format to achieve accurate decoding and conversion results.
• Utilize the filename_prefix parameter to organize your saved files systematically, especially when working with batch processes or multiple projects.
• Adjust the preview_ev parameter to fine-tune the tonemapped preview's exposure, helping you better visualize the HDR content in standard dynamic range.
• Keep the save_exr parameter enabled if you need to preserve the decoded HDR images for further editing or archival purposes.

Gear · LogC3 Decode + Save EXR Common Errors and Solutions:

Error: "Invalid image format"

• Explanation: This error occurs when the input image is not in the expected LogC3 format.
• Solution: Verify that the input image is correctly encoded in LogC3 and within the [0,1] range before processing.

Error: "Failed to save EXR file"

• Explanation: This error might arise if there are issues with the output directory permissions or if the directory does not exist.
• Solution: Ensure that the output directory is correctly set up and that you have the necessary permissions to write files to it. Check the directory path for any errors or typos.

Error: "Preview exposure value out of range"

• Explanation: This error indicates that the preview_ev value is outside the allowed range of -8.0 to 8.0.
• Solution: Adjust the preview_ev parameter to fall within the specified range to ensure proper tonemapping of the preview image.