The analog output of my CCD sensor is reverse! and it's digital output is noisy. why?

I have a linear and color CCD (RGB) with low sensitivity or response, according to it's data sheet. My work is based on FPGA and VHDL.
analog output of this CCD sensor ,observed on oscilloscope screen, has below typical shape. but it acts reversely. that is, the differences between the reference level and data level will be max while dark source and it will be min (near to zero) while max of intensity of light source!!! I don't know why it act reversely??? Moreover, after the converting of analog to digital, the observed output of AFE is noisy in both states of dark source and light source.
can you help me?

Welcome to ETO, sara_s!

sara_s said:

... but it acts reversely. that is, the differences between the reference level and data level will be max while dark source and it will be min (near to zero) while max of intensity of light source!!! ...

Click to expand...

What you are describing makes no sense. Please provide a schematic of your test circuit.

sara_s said:

I have a linear and color CCD (RGB) with low sensitivity or response, according to it's data sheet.

Click to expand...

What part number?
We need to see the data sheet to.