Enhanced Image processing (gamma, exposure, contrast, burn)

  • Hi,

    since a while I observe a lack of image processing. Often I see Enscape renderings and think, a better image processing would help a lot - dark areas are to dark, the image looks like based on a linear output only.

    For example if I think back on my first time testing Maxwell (some years in the past) I remember me to be impressed by the natural look of colors and contrast. I thought that this must be one of the key features to make an image best looking. The last years I used Vray and one of my favorite features is the output curve correction. It allow me to setup a curve like known from analog films - a flat upper curve keeps details in bright areas.

    An other good way for an easy control is to adjust an image by burn value, contrast and exposure. (see screenshot of Vray controls)

    Auto exposure - often I miss a more complex auto exposure. It seems to adjust at the brightest points only, most at the background sky so that the foreground main object is to dark. Modern cameras are using multi field calculations. Attached an example where the auto exposured image shows a strange wide unused upper range at the histogram. Maybe there is a little bright pixel at the image that is used as reference for the auto exposure process.

    An other example show that I need to apply a strong gamma correction to catch the strong contrasts. Here it would be helpful to get a control for exposure/burn/gamma.

    Auto contrast - attached an example where I compare auto contrast on and off. Here the auto contrast cut away the bright areas, the automatic worsen the image.

    Contrast - the current slider doesn't allow to choose a lower contrast, only higher contrast is supported yet.

    Sorry, it's looks like a lot of work - the automatic modes needs to be refined and a way to catch high contrast is missed, a burn option should be the solution. A linear color mapping isn't enough.

    It could be nice if the automatic could be shifted by the user to more attention to the bright or dark areas. So, the user could choose the mood like needed - for example high key or low key. A fix automatic can't decide what is the goal.




  • Thanks for the detailed comparisons.

    • Enscape's Auto Exposure uses a histogram to maximize the range of visible screen content. Not only the brightest point is considered. The purpose of auto exposure is not an even usage of the histogram! It should control the position of the middle-grey.
      But of course it can be made more sophisticated to more match a photography auto exposure.
    • The Auto Contrast is also based on a histogram and maximized the black/white range. If you have an image that fully uses the color spectrum, nothing changes. It should help at your second image to utilize the color range.

    The other points are good ideas, we might add them in future releases.

  • OK, now I know why it not works. ;) But I hope a solution will be found. The Enscape experience shouldn't suffer at the end of all the impressive calculations and mega byte of code. ;)

    If I understand you right, than the auto contrast shouldn't cut the histogram like shown.