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I recently bought a Mits. 73837. With the SharpEdge function turned off, the Sharpness setting has absolutely no effect at all--from 0 to 63 (max) there is zero change in picture.


If Sharpness is set at zero, and SharpEdge is turned on, there is no difference at all. However, if Sharpness is raised, it now has a definate effect with ringing becoming noticeable at around a Sharpness of 17.


1. What is the difference between sharpness & edge enhancement?

2. Is edge enhancement "bad" to use if no ringing is present, or does it negatives other than ringing?

3. Is using the Sharpness & SharpEdge combo. above better than having SharpEdge off with Sharpness having no effect?
 

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Greetings


Sharper image ... less detail. the control functions like an oxymoron.


regards
 

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Quote:
1. What is the difference between sharpness & edge enhancement?

They are both loose terms for a variety of different operations, and are often interchanged.

Quote:
2. Is edge enhancement "bad" to use if no ringing is present, or does it negatives other than ringing?

If it isn't doing anything, then it can't be doing anything bad. But you have to be very careful to look at a variety of different material and patterns to be sure that it is in fact not doing anything.

Quote:
3. Is using the Sharpness & SharpEdge combo. above better than having SharpEdge off with Sharpness having no effect?

If you have it turned on and sharpness down, that's basically the same then as having it turned off if there isn't a difference. If you want to use the sharpness control then obviously you need to turn it on.


I am not inherently against sharpness/edge enhancement operations per se, when used sparingly and intelligently by the end-user on the actual display resolution, rather than imposed on the content at the content's resolution limits, sharpness features aren't inherently evil.


It's just when either forced on you by the content producers, or misapplied by displays or end-users that it is often evil. Generally speaking though, you want to have your frequency response essentially flat, and if you boost up a little bit, you need to understand what you're doing, why, and do it very sparingly, and hopefully with a really high quality algorithm. Otherwise, the simple answer is that I would tend to agree that using sharpness features is bad, but that's kind of an oversimplification, but a safer generalization to make.
 

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As mentioned by Chris ...


Sometimes you have to use sharpness to make something really crappy looking ... look bearable to watch. The function has its limited uses.


regards
 

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I am not a pro-calibrator, but this is my understanding.


Traditional sharpness controls are for analogue inputs.

It should not be need for digial inputs. The display may bypass sharpness control on digital inputs which is why it has no visible effect.


With analog it is a high frequency gain (contrast in fine image details) control. Analog signals can lose high frequency signal strength due to bandwidth and signal noise and with dvd filters on the video dacs rolling off the high frequency response.


Sharpness control increases / decreases amplitude of the high frequencies.

If it is overdone it can introduce edge artifacts and magnify signal noise, also some sources are optomized for displays expected to have poor high frequency response, they have edge-enhancement already that becomes more exagerated with better high frequency response.


To set sharpness for analogue inputs. I use DVE horizontal frequency sweep test pattern and adjust the sharpness control to make the black and white lines the same contrast (white/black) across the screen, as high frequency response rolls off the lines will appear to become less white/black more grey. I then check with the DVE sharpness test pattern to see if ringing is visible at normal viewing distance. Note normal dvds will have less visible ringing than the DVE disc because the test disc has good frequency response, virtually all normal dvds are pre-smoothed, high frequency response is rolled off, this is to reduce line twitter as dvds are stored interlaced, it also reduces the amount of data that needs to be encoded on the disc.


For Blu-ray and hidef tv using hdmi inputs sharpness controls should not be needed.


Edge Enhancement is added to the signal. On some dvds/blu-rays it is added because they are expected to be dislayed on displays with poor high frequency response. Edge Enhancement peaks the high frequency response, it increases the contrast/visibility of fine details but can cause ringing and reduce the clarity/resolution of fine details. The idea is to make the image look sharper at normal viewing distances. On crt it works because of the beam focus and viewing distance making the ringing less noticeable, while the increase in contrast makes the details stand out more. On large digital displays it can make objects look like some ones drawn round them with a white or light grey pen.

Edge Enhancement on the display should not be needed for digital displays, but might increase perceived sharpness depending on viewing distance and display size. The smaller the display and larger the viewing distance the more likely it will make the image appear to look better, as it will be blurring fine details by using ringing (the fine details lost and ringing used is too small for you to easily see) to enhance the contrast of details. While the larger the display and closer the viewing distance the more likely it will make the image look worse. You are losing fine detail you could see and replacing it with odd looking ringing artifacts you can also see.


Other enhancements used on some dvds/blu-rays are filtering and digital noise reduction. They are designed to remove intrusive film grain and any damage and dirt on the original film print, in effect to clean up the image. But in practice they can be overdone, some people view film grain as intrinsic to the picture quality and it can remove fine details as well leading to a waxy, computer game / oil painting look with too smooth images. Peoples skin no longer has pores and is too uniform in color it no longer looks photo-realistic. Digital noise reduction on displays should not be needed on good transfers. Special digital noise reduction algorithims on some displays are designed to target mosquito noise, frame noise, and block noise caused by poor encoding on low bit rate standard definition digital tv and poor quality dvds.


For analogue inputs on a fixed pixel digital display another issue effects image resolution. Pixel phase. If on the DVE disc horizontal frequency sweep test pattern the finest lines are just a block of light grey. The pixel phase is wrong, you need to adjust the tracking/phase/clock/fine-sync, or whatever the display calls it. See
http://archive.avsforum.com/avs-vb/s...?postid=681112


Digital Sharpness / Edge Enhancement. Present on some Blu-ray player post-processing, some video processors and maybe some displays. These operate purely in the digital domain, altering the digital values of pixels by using algorithims to identify edges and/or details. They do not cause the ringing associated with analogue methods. At worst they can be seen as distorting the original source image by exagerating the contrast/visibility of edges and details. At best they can be seen as enhancing the picture quality or compensating for a displays inherently lower contrast at sharp edges and in fine details. I do not know about flat pannels but on projectors due to the glass of the lens, contrast between black and white far apart from each other will be higher than contrast between black and white right next to each other.


For digital inputs on fixed pixel displays another issue effects resolution. Pixel to pixel mapping. Ideally you want no overscanning and the source to be the same resolution as the display. So each single pixel being output by the source is being displayed as a single pixel by the display. Rescaling due to overscanning or source-display resolutions not matching, softens the image as it is spreading detail from one source pixel across more than one display pixel, often in an uneven manner.
 

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There is no distinction between sharpness and edge enhancement today - analog video sources are digitized before they are processed (or displayed) in the panel. There are no analog controls any longer. There are still sharpness controls labeled "sharpness" in digital TVs. Some sharpness controls affect horizontal and vertical edges while others only affect "sharpness" in one direction. Edge Enhancement controls always seem to "enhance" edges in both directions. Both reduce visible detail by adding false contours.


It can be difficult or impossible to see the effects of sharpness or edge enhancement without the right test pattern. You did not mention if you were using a test pattern or not. If you were not, your experimentation may have revealed nothing useful. The correct test pattern has black vertical and horizontal lines on a gray background. As you advance the sharpness or edge enhancement control, white edges will appear betweent the black lines and gray background. It's very difficult to see that happen in moving images unless the control is very very severe - but even a small amount of "invisible" sharpening or edge enhancement causes a loss of detail. "Off" or "Zero" may or may not be the right setting for these controls - some of them will actually make edges SOFTER (like they are out of focus) if you turn the control "Down" too far. Other's are "off" when they are set to zero - you can't know in advance without looking at the sharpness test pattern (black lines on gray background.
 
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