OpenAI image API bug appears to improve when images are resized to 2048×2048

RexDouglass · x · 2026-07-24

Users found that when sending images to the OpenAI API, resizing them to at most 2048×2048 can avoid a GPT-5.6 bug that places bounding boxes in seemingly random positions.

The cited example shows before/after behavior on a chessboard image: without downscaling, detections become oddly arranged in straight rows or evenly spaced clusters; after resizing, the boxes align far more sensibly. The post frames this as a practical workaround for a model/image-processing issue.

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