Fix a bug in preprocessing when filters=box only

lib/pairwise_transform_utils.lua

@@ -49,6 +49,7 @@ function pairwise_transform_utils.preprocess(src, crop_size, options)
       dest = data_augmentation.color_noise(dest, options.random_color_noise_rate)
       dest = data_augmentation.overlay(dest, options.random_overlay_rate)
       dest = data_augmentation.unsharp_mask(dest, options.random_unsharp_mask_rate)
+      dest = iproc.crop_mod4(dest)
    else
       dest = pairwise_transform_utils.random_half(dest, options.random_half_rate, options.downsampling_filters)
       dest = pairwise_transform_utils.crop_if_large(dest, math.max(crop_size * 2, options.max_size))