AVS Forum Special Member
Join Date: Jan 2008
Location: Copenhagen, Denmark
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It means measuring the contrast of a 4x4 checkerboard pattern (the average brightness of the white squares divided by the black). This can be regarded as a really bad scenario for contrast as the more light you put out the more light contamination you get. It is also not very relevant for movies as the average frame has much, much less light.
Native sequential on off contrast is what a projector can achieve with a fully white and then a fully black frame. This is also close to the contrast you can expect in very dark images with only small portions of the screen with bright objects. For the jvcs this is in the 25k-120k range depending on iris setting, throw and model.
Dynamic contrast is the difference between a fully white and fully black frame also using dimming of the light source for the black frame. Thus can be achieved by either direct dimming the light source or having a dynamic iris that shuts down in dark frames. Dynamic contrast is useful for decreasing the black floor but is limited as it also dims the white at the same time and can cause brightness compression, brightness pumping and other artifacts. A moderate multiplier of the native contrast really does help to improve the image though.