Thermal imager arrangements

Claim 2

A thermal imager data processing arrangement comprising: an input for receiving a full range of pictorial digital data from a thermal imager; digital data processing means for applying a transform to the digital data to produce at a first output a windowed analogue signal for connection to a display means so that an image of enhanced contrast is formed on said display means, the gain and offset of said analogue signal compared to said received data being determined by the transform which is applied; and a second output at which the full range of pictorial data in digital form is available.

Claim 3

An arrangement as claimed in claim 1 wherein the transform which is applied is determined by monitoring the received data.

Claim 4

An arrangement as claimed in claim 1 and including means arranged to sort the received data into a histogram showing the numerical distribution of data digits according to their value.

Claim 5

An arrangement as claimed in claim 1, wherein the transform is applied to the received data by generating a look-up table according to the transform to which the received data is applied.

Claim 6

An arrangement as claimed in claim 1 wherein the pictorial data is received as successive frames separated by field blanking periods and in which each frame of data is ordered into a histogram showing the numerical distribution of the data digit values in that frame.

Claim 7

An arrangement as claimed in claim 5 and wherein the transform to be applied to a frame of data is determined during a field blanking period.

Claim 8

An arrangement as claimed in claim 1 including means for determining the transform without reference to the received data.

Claim 9

An arrangement as claimed in claim 4, including means arranged to sort the received data into a histogram having two sigma points and showing the numerical distribution of data digits according to value and wherein the two sigma points of the histogram are determined to calculate the range of values of the output signal.

Claim 10

An arrangement as claimed in claim 8 wherein the two sigma points are determined by summing the numnber of data digits at each value successively, from the lowest value for the low two sigma point, and from the highest value for the high two sigma point until a predetermined percentage of the total number of data digits making up the histogram is exceeded, the values at which the sums exceed the percentage being allocated as the two sigma points.

Claim 11

An arrangement as claimed in claim 1 and including means for applying a predetermined transform to the received data when substantially all the data is contained within a relatively small range of data values.

Claim 12

An arrangement according to claim 1 wherein means are provided to display information derived from the analogue data simultaneously with information derived from the digital data.

Claim 13

A thermal data processing arrangement comprising: an input for receiving successive frames of pictorial digital data from a thermal imager; and digital data processing means for applying a transform to the digital data to produce at a first output a windowed signal for connection to a display means so that an image of enhanced contrast is formed on said display means for each frame of said data, the gain and offset of said windowed signal as compared to said received data being determined by the transform which is applied, said data processing means: producing a histogram for each frame of received data showing the numerical distribution of the data digits according to their value; selecting a range of output values from the histogram which after application of the transform will correspond to peak black and peak white levels, the range being determined by summing the number of data digits at each value successively from both the lowest and highest values to one of two points until a predetermined percentage of the total number of data digits making up the histogram is exceeded, said range of output values from said histogram corresponding to the values of said data digits at said two points; and applying a transform to the data in the selected range of output values from said histogram by generating a look-up table and applying each selected data digit to the look-up table, the output from said look-up table corresponding to said windowed outut signal.

Claim 14

A thermal data processing arrangement comprising: an input for receiving successive frames of pictorial digital data from a thermal imager; and digital data processing means for applying a transform to the digital data to produce at a first output a windowed signal for connection to a display means so that an image of enhanced contrast is formed on said display means for each frame of said data, the gain and offset of said windowed signal as compared to said received data being determined by the transform which is applied, said data processing means: producing a histogram for each frame of received data showing the numerical distribution of the data digits according to their value; selecting a range of output values from the histogram which after application of the transform will correspond to peak black and peak white levels, the range being determined by summing the number of data digits at each value successively from both the lowest and highest values to one of two points until a predetermined percentage of the total number of data digits making up the histogram is exceeded, said range of output values from said histogram corresponding to the values of said data digits at said two points; and applying a transform to the data in the selected range of output values from said histogram by generating a look-up table and applying each selected data digit to the look-up table, the output from said look-up table corresponding to said windowed outut signal.