4 Functionality
4.7
Digital Gain and Offset
Gain x1, x2, x4 and x8 are digital amplifications, which means that the digital image data are
multiplied in the camera module by a factor 1, 2, 4 or 8, respectively. It is implemented as a
binary shift of the image data, which means that there will be missing codes in the output
image as the LSB’s of the gray values are set to ’0’. E.g. for gain x2, the output value is shifted
by 1 and bit 0 is set to ’0’.
A user-defined value can be subtracted from the gray value in the digital offset block. This
feature is not available in Gain x1 mode. If digital gain is applied and if the brightness of the
image is too big then the output image might be saturated. By subtracting an offset from the
input of the gain block it is possible to avoid the saturation.
4.8
Grey Level Transformation (LUT)
Grey level transformation is remapping of the grey level values of an input image to new
values. The look-up table (LUT) is used to convert the greyscale value of each pixel in an image
into another grey value. It is typically used to implement a transfer curve for contrast
expansion. The camera performs a 12-to-8-bit mapping, so that 4096 input grey levels can be
mapped to 256 output grey levels. The use of the three available modes is explained in the
next sections. Two LUT and a Region-LUT feature are available in the MV1-D1312 camera series
(see Section 4.8.4).
For MV1-D1312-240 camera series, bits 0 & 1 of the LUT input are fixed to 0.
The output grey level resolution of the look-up table (independent of gain,
gamma or user-definded mode) is always 8 bit.
There are 2 predefined functions, which generate a look-up table and transfer it
to the camera. For other transfer functions the user can define his own LUT file.
Some commonly used transfer curves are shown in Fig. 4.44. Line a denotes a negative or
inverse transformation, line b enhances the image contrast between grey values x0 and x1.
Line c shows brightness thresholding and the result is an image with only black and white grey
levels. and line d applies a gamma correction (see also Section 4.8.2).
4.8.1
Gain
The ’Gain’ mode performs a digital, linear amplification with clamping (see Fig. 4.45). It is
configurable in the range from 1.0 to 4.0 (e.g. 1.234).
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Summary of Contents for CameraLink MV1-D1312 series
Page 1: ...User Manual MV1 D1312 I CameraLink Series CMOS Area Scan Camera MAN041 09 2010 V2 5...
Page 2: ......
Page 4: ...2...
Page 8: ...CONTENTS 6...
Page 14: ...2 How to get started CameraLink 12...
Page 24: ...3 Product Specification 22...
Page 72: ...4 Functionality Figure 4 56 Unsharp Mask Examples 70...
Page 110: ...8 Mechanical and Optical Considerations 108...
Page 112: ...9 Warranty 110...
Page 114: ...10 References 112...
Page 118: ...A Pinouts 116...