黑底运动员汗水肖像

生成一张 4:5 竖版黑底运动员汗水肖像。中国女性短跑运动员站在纯黑影棚背景前，穿无标识深灰训练背心，肩颈和手臂有真实汗水高光，双手握着一条白色无字毛巾垂在胸前，目光坚定看向镜头。构图为胸口到头部近景，不出现跑道或健身房。灯光为左右窄边缘光加正面很弱补光，黑背景中只有汗水和肌肉线条被照亮。色调黑、深灰、冷白高光和自然肤色，强烈克制。100mm 镜头，人物比例真实，肌肉自然不过度夸张。画面内不要出现任何可读文字、logo、水印、品牌、号码布或标识。

Create a 4:5 vertical black-background athlete sweat portrait. A Chinese female sprinter stands in front of a pure black studio background, wearing an unbranded dark gray training tank. Real sweat highlights appear on her shoulders, neck, and arms. She grips a white text-free towel hanging in front of her chest and looks firmly into the camera. Close composition from chest to head, with no track or gym visible. Lighting uses narrow rim lights on both sides plus very weak frontal fill, so only sweat and muscle lines emerge from the black background. Palette: black, dark gray, cool white highlights, and natural skin tones; intense and restrained. 100mm lens, realistic proportions, natural athletic build without exaggeration. No readable text, logo, watermark, brand, bib number, or mark anywhere.