1. An image signal processing system comprising: data conversion logic configured to convert unsigned input image data of raw or RGB format deriving from a digital image sensor into signed input image data of raw or RGB format to preserve negative noise from the sensor; and an RGB-format image processing pipeline comprising demosaicing logic configured to convert the signed input image data into RGB format when the signed input image data is of raw format, wherein the RBG-format image processing pipeline is configured to process the signed input image data of RGB format into processed signed RGB output image data.