Parametric logarithmic type image processing for contrast based auto-focus in extreme lighting conditions

Abstract

While most of state-of-the-art image processing techniques were built under the so-called classical linear image processing, an alternative that presents superior behavior for specific applications comes in the form of Logarithmic Type Image Processing (LTIP). This refers to mathematical models constructed for the representation and processing of gray tones images. In this paper we describe a general mathematical framework that allows extensions of these models by various means while preserving their mathematical properties. We propose a parametric extension of LTIP models and discuss its similarities with the human visual system. The usability of the proposed extension model is verified for an application of contrast based auto-focus in extreme lighting conditions. The closing property of the named models facilitates superior behavior when compared with state-of-the-art methods.

High Dynamic Range Imaging by Perceptual Logarithmic Exposure Merging

“…Next, given the parametric extension of the LTIP model by Florea and Florea (2013), we asked which is the best value for the parameter m. As shown in Fig. 4, bottom row ((e)-(h)), the best visual results are obtained for m = 1, which corresponds to the original LTIP model.…”

“…The supplemental calculus associated with the non-linearity of LTIP operation could easily be trimmed out by the use of look-up tables, as shown by Florea and Florea (2013).…”

“…A summary of existing models may be followed in the work of Navarro et al (2013). Recently, parametric extensions of LTIP models have also been introduced (Panetta et al, 2011;Florea and Florea, 2013). LTIP models are summarized in Table 2.…”

“…It has previously been pointed to the similarity between the LTIP generative function and the CRF (Florea and Florea, 2013). To show the actual relation between the LTIP generative function and the CRF, we considered the database of response functions (DoRF) (Grossberg and Nayar, 2004), which consists of 200 recorded response functions of digital still cameras and analogue photographic films.…”

Robust Eye Gaze Estimation

“…An extension to Logarithmic Type Image Processing (LTIP) is presented in [4]. The parametric extensions of LTIP models were used to built a reliable autofocus mechanism for cameras working under extreme light conditions.…”