43. IJ printer MTF measurement - 2011

43. IJ printer MTF measurement - 2011 - Purdue University...

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Unformatted text preview: Purdue University HP-Purdue Confidential ¡ Woonyoung Jang Prof. Jan P. Allebach Electronic Imaging Systems Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette, IN 47907 Purdue University HP-Purdue Confidential ¡ • What is MTF • Test target page design • Scanner color calibration • MTF measurement method in L*a*b* uniform color space • HVS model for the perceptibility of the color modulation • Experimental results • Conclusion • Future work Purdue University HP-Purdue Confidential ¡ MTF of an IJ printer ¢£ Print a test target page ¤£ Scan the printed target ¡£ Analyze scanned data Test Target Page Purdue University HP-Purdue Confidential ¡ • The MTF of an imaging system The MTF is the magnitude of the OTF (optical transfer function) as If the input signal x (·) is an impulse, then the MTF can be obtained by calculating | Y ( f )| / | Y (0)|, where Y ( f ) is the impulse response of the system. The MTF describes how much the system attenuates the input modulation signal as a function of frequency. • MTF measurement by using a set of sinusoidal signals Measure the output response for a set of sinusoidal signals. Extract the output magnitude at the given frequency for each sinusoidal signal. Normalize the extracted output magnitudes and estimate the MTF curve. Purdue University HP-Purdue Confidential ¡ B W R C M Y K G 3D color cube a* L* b* x [ n ] = cos(2 f n ) + . . . . . . Color modulation signal measured in L*a*b* uniform color space in E unit A’ B’ A B L*a*b* color space Purdue University HP-Purdue Confidential ¡ 255 ( M) B W R C M Y K G Color modulation direction p ( x ) = + cos(2 f x ) - x + 0 ( W) Spatial angle • Parameters for generating a color patch Color modulation direction: from the vertex W to another vertex Parameters in a modulation signal: bias( ), amplitude( ), frequency ( f ) Spatial angle = 0 º = 90 º Purdue University HP-Purdue Confidential ¡ • What is MTF • Test target page design • Scanner color calibration • MTF measurement method in L*a*b* uniform color space • HVS model for the perceptibility of the color modulation • Experimental results • Conclusion • Future work Purdue University HP-Purdue Confidential ¡ • For a given color modulation direction, amplitude , and spatial angle , Bias : 15 levels [4, 8:20:248, 252] Frequency f : 9 points [10 20 30 40 50 60 80 100 120] cycles/inch Size of one color patch: 0.53in 0.53in with margin Constant tone color patches for given bias level and amplitude » Two extreme constant tones: ( - ) and ( + ) • Visual aids and segmentation tools Information of bias, frequency, and angle shown in the page Position locating marks » Color patches are densely packed hard to locate the start points of the color patches » Type I (initial position), Type II (color patches), tick marks Purdue University...
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43. IJ printer MTF measurement - 2011 - Purdue University...

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