FluxResolutionPrepare

Overview

FluxResolutionPrepare crops and resizes an image to the closest legal resolution supported by Flux-family models. It optionally pre-upscales low-resolution inputs to a minimum megapixel budget, respects an optional user-supplied crop window, and reports the chosen aspect ratio along with crop efficiency metrics.

Inputs

image (IMAGE): Source tensor [1, H, W, C]. Batched inputs are not supported.
min_megapixels (FLOAT, default 0.95): Minimum megapixel target used when enable_pre_upscale is True. The node upsamples the image if the current pixel count is below this threshold.
enable_pre_upscale (BOOLEAN, default True): Toggles the pre-upscale pass. When disabled, the original resolution is used for cropping.
crop_width (INT, optional, default -1): Width of a user-specified region of interest. Values <= 0 disable the manual crop.
crop_height (INT, optional, default -1): Height of the manual crop ROI.
crop_x (INT, optional, default 0): Left offset of the manual crop (pixels, before pre-upscale).
crop_y (INT, optional, default 0): Top offset of the manual crop (pixels, before pre-upscale).

Outputs

image (IMAGE): Processed tensor sized to a Flux-compatible resolution.
ratio (STRING): Human-readable aspect label (e.g., 3:4, 9:21).
target_width (INT): Final width selected from the built-in Flux whitelist.
target_height (INT): Final height.
area_loss_percent (FLOAT): Percentage of the (pre-upscaled) working area discarded during cropping.
pre_scale_factor (FLOAT): Scale multiplier applied by the pre-upscale stage (1.0 when disabled or unnecessary).

Processing Notes

The node first pre-upscales by the minimum factor required to hit min_megapixels, using bicubic interpolation.
If a manual crop is specified, it is interpreted in original-image coordinates and mapped to the pre-upscaled space.
The best Flux resolution is chosen by minimizing scale deviation, area loss, and ratio error across a fixed candidate list (landscape/portrait pairs included).
Final cropping is centred unless constrained by the boundaries of the manual crop; resizing uses bicubic interpolation.

Tips

Feed the emitted ratio into UI labels/logs so you can audit whether the chosen aspect aligns with your prompt or downstream model.
When passing manual crop dimensions, ensure they leave enough room for the target aspect ratio; otherwise, the node will fall back to the nearest fit that clamps to image bounds.
Pair this node with MQBBoxMin and FitAspectHeadSafe to derive a subject-aware crop before committing to Flux sizing.*** End Patch

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