ios - 'inputEV'的含义

Question

CIFilter“CIExposureAdjust”中使用的键名“inputEV”是什么意思？

例如:

    CIFilter *exposureFilter = [CIFilter filterWithName:@"CIExposureAdjust"];
    [exposureFilter setValue:outputImage forKey:kCIInputImageKey];
    [exposureFilter setValue:[NSNumber numberWithFloat:5] forKey:@"inputEV"];
    CIImage *outputImage = [exposureFilter valueForKey:kCIOutputImageKey];

Answer 1

根据文档，这是曝光值:

This filter multiplies the color values, as follows, to simulate exposure change by the specified F-stops:

s.rgb * pow(2.0, ev)