How to measure "sharpness" of picture - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 
Thread Tools
post #1 of 13 Old 10-19-2002, 10:50 AM - Thread Starter
Member
 
sthong's Avatar
 
Join Date: Jul 2002
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
My picture appears a little "soft"... details a bit "blurry"... even more so than when I started tweaking my set. However, this is all subjective and I have no way of concretely measuring change or comparing to other people's sets. Perhaps my perception and expectations have changed over time ?

Regardless, is there a concrete way of measuring "sharpness", or accurateness of picture detail? Is this one of the AVIA test images? If so, which one?

thanks!

Steven
sthong is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old 10-19-2002, 05:20 PM
AVS Forum Special Member
 
Cheezmo's Avatar
 
Join Date: May 1999
Location: Plano, TX
Posts: 2,106
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 422 Post(s)
Liked: 298
Check out the Resolution patterns on Avia. Clear vertical stripes in the 6.75Mhz patch in the lower right corner would indicate you are getting the full resolution out of the DVD format.

Sharpness is usually abused (set to high) causing white highlights on vertical black lines as seen on the Avia sharpness pattern.

A good way to set it is to view the Avia sharpness pattern and lower sharpness until those white highlights go away. Now look at the resolution pattern across the top and see if the right edge has blurred into a gray mush. If so, you need to settle on a compromise between reducing the edge enhancement or reducing your resolution.

If you tell us what model TV you have you might be able to get some specific advice.

Other things that affect the apparent "sharpness" of the picture are focus, SVM (should be off), and convergence.

Steve Martin
former ISF Calibrator
If you can see my pixels, you are sitting too close.
Sony XBR75X940D, Sony XBR55X930D, Samsung UBD-K8500, Oppo BDP-103, Oppo BDP-93,
Cheezmo is offline  
post #3 of 13 Old 10-19-2002, 06:14 PM - Thread Starter
Member
 
sthong's Avatar
 
Join Date: Jul 2002
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks for the tip.

To your question, I have an Hitachi 57swx20b
sthong is offline  
Sponsored Links
Advertisement
 
post #4 of 13 Old 10-19-2002, 08:26 PM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
https://www.avsforum.com/avs-vb/showt...0&pagenumber=2

Check out that post....

This is what the TLV chart from AVIA should look like sort of..

This picture was taken from the showroom floor of CC with a 51" SWX 20B model, never been calibrated box stock... running a JVC DVD player in interlaced 480i MODE....


https://www.avsforum.com/photopost/da...lv_chart22.jpg
Mfusick is offline  
post #5 of 13 Old 10-19-2002, 08:40 PM
AVS Forum Special Member
 
Cheezmo's Avatar
 
Join Date: May 1999
Location: Plano, TX
Posts: 2,106
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 422 Post(s)
Liked: 298
Right. None of the vertical lines in that 6.75Mhz pattern should look darker than the others. That is a sign of some kind of EE altering the frequency response.

Steve Martin
former ISF Calibrator
If you can see my pixels, you are sitting too close.
Sony XBR75X940D, Sony XBR55X930D, Samsung UBD-K8500, Oppo BDP-103, Oppo BDP-93,
Cheezmo is offline  
post #6 of 13 Old 10-19-2002, 08:48 PM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
I was wondering about that...

My set at home does not do this.... Nor did it do it the second time I tried it.

Wonder what made that happen, or if it was the camera and the light or somthing with the photo and the way it was taken?

I don't recall seeing it that way... But it did come out like that in the photo..

You can still see the lines though... Which is good, especailly since it was a 480i signal. Most line doublers aren't that good. That's what I was testing really...
Mfusick is offline  
post #7 of 13 Old 10-19-2002, 09:34 PM - Thread Starter
Member
 
sthong's Avatar
 
Join Date: Jul 2002
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
On the lefthand side of the 6.75 mhz circle, I can see all virtical lines.. the rightmost 10-15 lines, are a little blurred.

In addition, I have the same "dark lines" as in your photo... appear every 6 lines. Not sure what those are...

Thanks.
sthong is offline  
post #8 of 13 Old 10-19-2002, 10:06 PM
AVS Forum Special Member
 
Cheezmo's Avatar
 
Join Date: May 1999
Location: Plano, TX
Posts: 2,106
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 422 Post(s)
Liked: 298
If they blur toward the outer edge, it would indicate that your focus (or perhaps just convergence) is not good all the way to the edge of the screen. The every nth line being darker thing is an indication of some kind of EE or sharpness circuit affecting the image. That could be an issue with the TV or the DVD player or both.

Steve Martin
former ISF Calibrator
If you can see my pixels, you are sitting too close.
Sony XBR75X940D, Sony XBR55X930D, Samsung UBD-K8500, Oppo BDP-103, Oppo BDP-93,
Cheezmo is offline  
post #9 of 13 Old 11-26-2002, 07:50 AM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
The "SWEET SPOT" of the lens assembly and lens barrel system is in the center.

One of the reasons why Hitachi re-developed the HD Wideneck CRT to be 17% larger at the face this year... So it could take more advatage of a larger lens barrel and lense system in the Super Contrast lens.

I you adjust overscan too much, the far edges will suffer convergence and focus problems. A little bit of overscan is good.

I think you manual focus will fix some of you issues...
Mfusick is offline  
post #10 of 13 Old 05-06-2003, 05:30 AM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
Quote:
Originally posted by Cheezmo
Right. None of the vertical lines in that 6.75Mhz pattern should look darker than the others. That is a sign of some kind of EE altering the frequency response.
This picture shows it good...

 

swx20b tlv chart close up.zip 193.46875k . file
Attached Files
File Type: zip swx20b tlv chart close up.zip (193.5 KB, 31 views)
Mfusick is offline  
post #11 of 13 Old 05-12-2003, 07:10 PM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
EDITED ****05/12/03
Mfusick is offline  
post #12 of 13 Old 05-12-2003, 07:27 PM
Advanced Member
 
spidey07's Avatar
 
Join Date: Oct 2002
Posts: 503
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Mike,

What's up with that resolution circle? I've seen that picture before and always wondered if you fixed it. Some service menu EE going on? From the conversion? Is it different for 1080i/540p and does it vary between interlace and progressive on the source?
spidey07 is offline  
post #13 of 13 Old 07-16-2003, 05:00 PM
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 29,681
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 608 Post(s)
Liked: 2725
There are many sharpness parameters in the service menu that can fix this..

Problem I found is that when I improve the Test pattern... the picture does not benifit... rather worsen with a softness (and No I am not some SVM addict)

So.... I put it back
Mfusick is offline  
Sponsored Links
Advertisement
 
Closed Thread Rear Projection Units

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off