Method for correcting integrating cavity effect for calibration and/or characterization targets

A method of correcting measured reflectance of an image acquired by an image acquisition device having an integrating cavity, the method comprising:

• obtaining values associated with the image;
• iteratively applying a non-linear correction function to the values to obtain an approximation of corrected reflectance values wherein a first approximation is obtained using:
• R
• 0
• ⁡
• (
• x
• )
• =
• M
• ⁡
• (
• x
• )
• 1
• +
• α
• ⁢
• ⁢
• M
• ⁡
• (
• x
• )
• where R is reflectance, M is measured reflectance and alpha is a parameter that depends on the geometry of the image acquisition device, and wherein a successive approximation is obtained using:
• Ri+1(x)=M(x)(1−αGoRi(x)),
• where G*R is an averaging kernel;
• and,
• selectively filtering the corrected reflectance values using a piecewise Gaussian filter.

A method of correcting measured reflectance of an image acquired by an image acquisition device having an integrating cavity, the method comprising:

• obtaining scanned values of the image;
• scaling the scanned values to obtain scaled values;
• applying a non-linear correction function to the scaled values to obtain an approximation of corrected reflectance values, wherein a first approximation is obtained using:
• R
• 0
• ⁡
• (
• x
• )
• =
• M
• ⁡
• (
• x
• )
• 1
• +
• α
• ⁢
• ⁢
• M
• ⁡
• (
• x
• )
• where R is reflectance, M is measured reflectance and alpha is a geometrically dependent parameter that depends on the geometry of the image acquisition device, and wherein the non-linear correction function is applied to obtain a successive approximation using:
• Ri+1(x)=M(x)(1−αGoRi(x)),
• where G*R is an averaging kernel;
• and,
• selectively applying a piecewise Gaussian filter to the corrected reflectance values.

A method of correcting measured reflectance of an image acquired by an image acquisition device having an integrating cavity, the method comprising:

• obtaining scanned values of the image;
• applying a non-linear correction function to the scanned values to obtain a first approximation of corrected reflectance values;
• filtering the approximate corrected reflectance values;
• and,
• applying the non-linear correction function to obtain a successive approximation of the corrected reflectance values, wherein the successive approximation is obtained using:
• Ri+1(x)=M(x)(1−αGoRi(x)),
• where R is reflectance, M is measured reflectance, alpha is a geometrically dependent parameter, and G*R is an averaging kernel.

A method of correcting measured reflectance of an image acquired by an image acquisition device having an integrating cavity, the method comprising:

• obtaining scanned values of the image;
• applying a non-linear correction function to the scanned values to obtain a first approximation of corrected reflectance values, wherein the first approximation is obtained using:
• R
• 0
• ⁡
• (
• x
• )
• =
• M
• ⁡
• (
• x
• )
• 1
• +
• α
• ⁢
• ⁢
• M
• ⁡
• (
• x
• )
• where R is reflectance, M is measured reflectance and alpha is a parameter that depends on the geometry of the image acquisition device;
• filtering the approximate corrected reflectance values;
• and,
• applying the non-linear correction function to obtain a successive approximation of the corrected reflectance values, wherein the successive approximation is obtained using:
• Ri+1(x)=M(x)(1−αGoRi(x)),
• where R is reflectance, M is measured reflectance, alpha is a geometrically dependent parameter, and G*R is an averaging kernel.

A system for correcting measured reflectance of an image affected by an integrating cavity, the system comprising:

• a scanner operative to obtain scanned values of the image;
• and,
• a processor operative to apply a non-linear correction function to the scanned values to obtain a first approximation of corrected reflectance values, filter the approximate corrected reflectance values using a piecewise Gaussian filter and apply the non-linear correction function to obtain a successive approximation of the corrected reflectance values, wherein the successive approximation is obtained using:
• Ri+1(x)=M(x)(1−αGoRi(x)),
• where R is reflectance, M is measured reflectance, alpha is a geometrically dependent parameter, and G*R is an averaging kernel.