Wedding Pictures

Western wedding pictures pose an interesting dilemma. We want to reduce the contrast (compared to the realistic value) to hide skin blemmish and give pictures that ``dreamy'' feel. Yet, at the same time, we want to preserve highlight details. These two objectives are contradictory if we can only adjust $\gamma _c$. If we reduce $\gamma _c$, we reduce the appearance of skin blemish, but we also wipe out highlight details. If we increase $\gamma _c$, we get back some of the highlight details, but we also expose skin blemish.

The solution is to use a curve that is not exactly following $o = i ^ {\gamma_c}$. Normalized skin tone values do not exceed 0.67 (gamma corrected, normalized), while highlight values usually start at 0.85. We can now break the correction curve into two parts. The first part has a reduced $\gamma _c$ to reduce skin blemish, and the second part has an increased $\gamma _c$ to improve highlight details.

Figure 4.1: This is the ``original'' picture. The ICC profile of the camera is applied to translate to normal sRGB color space, and the brightness is adjusted not to saturate any important pixels. Details on the wedding gown are preserved, but the skin tone looks too dark, and there is too much contrast.

Figure 4.2: This is the same picture as figure 4.1, except that I crank up brightness to lighten up the skin tone. Note that most of the details on the wedding gown is washed out.

Figure 4.3: This is the same picture as figure 4.1, except that I use a very low $\gamma _c$. Compared to figure 4.1, this version has lightened skin tone, and all the highlight is preserved. However, the skin tone has too little contrast, and the picture looks too flat.

Figure 4.4: This is based on the same picture as figure 4.1 (same exposure, no brightness correction), but a special ``fix-up'' curve is applied (after ICC profile application). This final image has lowered contrast and increased brightness for skin tone, but intensified contrast for highlight. Note all details on the wedding gown remain visible, while the skin tone looks ``pleasant'' and more lively than figure 4.3.