复印彩色文献和原稿、制作显微镜照片、以及在阴天下摄影时,都希望所得的照片反差高、色彩鲜亮。阴天摄影时,被摄体的反差和色彩亮度降低。这时若使用反差略高的底片,便可印制出色彩鲜亮的照片。但是如反差过高,则 Photocopying color documents and manuscripts, making microscopic photographs, and photographing in the dark, we all hope that the resulting photographs will have high contrast and bright colors. When shooting in cloudy weather, subject contrast and color brightness decrease. At this moment, if you use a negative film with a slightly higher contrast, you can print brightly colored pictures. However, if the contrast is too high, then