Elise, I design products for radiologists and I have a background in neuroscience. Your question as stated may be too broad. Let me breakdown your question first:
*how sensitive is *the human eye o changes in rightness? - we are sensitive on some level to a massive amount of changes, wikipedia dynamic range > Equally a person can see objects in starlight (although colour > differentiation <http://en.wikipedia.org/wiki/Color_vision> is reduced at > low light levels) or in bright sunlight, even though on a moonless night > objects receive 1/1,000,000,000 of the illumination they would on a bright > sunny day: that is a dynamic range of 90 dB. > - mediums such as CRT displays have a paltry contrast ratio of like 100x (if you physically measure the whitest white it puts out 100x more light than the blackest black), whereas print film is more like 1000x. So mediums cannot reproduce the types of changes in the real world. That is why photographers have to work so hard to fit the real world into the medium :) (too much dynamic range in a scene and you're getting clipping at white or black!). So, the human eye is how sensitive is *the human eye* to changes in rightness? - which human? radiologists can have high sensitivity to small changes in brightness that may be pathological, but unseen by the untrained. designers can see single pixels that are #CCCCCC instead of #DDDDDD in a sea of millions of pixels. experience builds sensitivity. - the human eyes at first levels in the retina is made for detecting and boosting change. Individual neurons will negate output from neighbours to boost contrast of edges. For example, white text on a black background is perceived as a brighter than on a black background. At a deeper level in the cortex visual system there is object processing that negates changes in brigthness across an object (we don't see changes across a wall being struck by different light sources), and boosts changes between objects (but we easily see a similarly lit object as standing out from the wall). Our eyes are first and foremost designed as a system for visual perception. how sensitive is the human eye *to changes in brightness?* ** - as mentioned by others, simultaneous comparison and memory comparison are two very different types of "change" - side by side stimulus change, versus stimulus/memory change When I've been asked questions like this as you have, usually they are starting from the vantage point of. "Let's find out about how the eye works, and see if there is research that studies the very thing we are working on to get us our answer." Rather, it is more like "take the potpouri of research which tells us about complexities of visual perception and use that as a starting point to envision some designs that may work on the problem." Usually the best use of this human science is to aid/inform the intuition of the designer. Rarely are the answers in "the back of the textbook" with this stuff... if you provide us more context we maybe able to help more. Navid On Wed, J un 4, 2008 at 3:09 PM, Elise Edson <[EMAIL PROTECTED]> wrote: > Specifically, how sensitive is the human eye to changes in brightness? > > ________________________________________________________________ Welcome to the Interaction Design Association (IxDA)! To post to this list ....... [EMAIL PROTECTED] Unsubscribe ................ http://www.ixda.org/unsubscribe List Guidelines ............ http://www.ixda.org/guidelines List Help .................. http://www.ixda.org/help
