# Description

In this article, a camera response formation model is proposed to accurately predict the responses of images captured under various exposure settings. Differing from earlier works that estimated the camera relative spectral sensitivity, our model constructs the physical spectral sensitivity curves and device-dependent parameters that convert the absolute spectral radiances of target surfaces to the camera readout responses. With this model the camera responses to miscellaneous combinations of surfaces and illuminants could be accurately predicted, thus creating an "imaging simulator", by using which the colorimetric and photometric research based on the cameras would be much of convenience.

# Figures

Figure 1. The L-curve of the regularization. The circle denotes the corner of L-curve, corresponding to the optimal regularization parameter $\lambda$

Figure 2. The training (plain patches) and testing (hatched patches) samples in our experiments. 44 repeated neutral patches around DSG color checker were discarded through the work

Figure 3. The spectral radiances of 48 selected training samples in the experiments

Figure 4. Nikon D3x's normalized spectral sensitivities estimated by different methods

Figure 5. Mean CIEDE2000 color difference over 48 training sample under different capture settings

Figure 6. The distribution of training samples in CIELAB $a^*b^*$ plane, the radius of circle denotes five times of the mean color difference over five capture settings of our model

# Reference

• B. K. P. Horn and R. W. Sjoberg, "Calculating the reflectance map," Appl. Opt. 18, 1770–1779 (1979).
• M. M. Darrodi, G. Finlayson, T. Goodman, and M. Mackiewicz, "Reference data set for camera spectral sensitivity estimation," J. Opt. Soc. Am. A 32, 381–391 (2015).
• A. Getman, T. Uvarov, Y. Han, B. Kim, J. Ahn, and Y. Lee, "Crosstalk, color tint and shading correction for small pixel size image sensor," in International Image Sensor Workshop, (2007), pp. 166–169.
• B. Dyas, "Robust color sensor response characterization," Color and Imaging Conference pp. 144–148 (2000).
• P. Urban, M. Desch, K. Happel, and D. Spiehl, "Recovering camera sensitivities using target-based reflectances captured under multiple led-illuminations," in Proc. of Workshop on Color Image Processing, (2010), pp. 9–16.
• More...

Feel free to contact jqx1991(at)gmail(dot)com with any suggestions/corrections/comments.