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Guide: GREYSCALE CALIBRATION FOR DUMMIES - Page 6

post #151 of 258
Great writeup!

Gonna be using it soon, just ordered a Chroma 5 with Calman
post #152 of 258
Thread Starter 
Quote:
Originally Posted by ElwayLite View Post

Great writeup!

Gonna be using it soon, just ordered a Chroma 5 with Calman

Thanks! But you won't need my writeup if you're using CalMAN. Just follow the CalMAN instructions. My guide's for those using ColorHCFR as HCFR doesn't have any instructions or hand-holding at all, just the basic tools and graphs.

Kal
post #153 of 258
Really, did not know that Calman was that detailed and actually instructed you. Ive seen a calibrator use it a few times, but it looked a tad intimidating.

Still a good read for getting an idea of what the heck is going on
post #154 of 258
Can gray scale (on a front projector) be done with just a calibration disc? if so, which one? Thanks.
post #155 of 258
Thread Starter 
Quote:
Originally Posted by Jim McC View Post

Can gray scale (on a front projector) be done with just a calibration disc? if so, which one? Thanks.

No. At least not a very good calibration as our eyes are very bad colour measurement devices.

A reasonable good meter that'll do 100 times better than your eyes ever could are not expensive. See my FAQ: Which meter is right for me? or read the guide.

Kal
post #156 of 258
Hey Kal, this guide is a lifesaver, I just have a few questions:

Is the correct Gamma supposed to be 2.20 or 2.22? I noticed that the default in the HCFR is 2.22, but the guide states that, "These monitors are designed for a ruler flat 2.20 response. "

Also, I have an LCD and at the 100% window, I get about 43 ftl, is it worth it to decrease contrast? If I do, the curve is not as straight but the avg. gamma may be closer (2.22 vs. 2.20?)

Any advice on powersave and backlight options?

I was wondering, on the previous page here, whether or not you could use the same meathod to set contrast that you use to set brightness (relationship between 10 IRE and 100 IRE)

Thanks again!
post #157 of 258
Thread Starter 
Quote:
Originally Posted by vigilante1 View Post

Hey Kal, this guide is a lifesaver, I just have a few questions:

Is the correct Gamma supposed to be 2.20 or 2.22? I noticed that the default in the HCFR is 2.22, but the guide states that, "These monitors are designed for a ruler flat 2.20 response. "

2.20 and 2.22 are so close that frankly they're the same. I do talk in my guide as to what's the correct gamma and how people over the years have argued over what the correct gamma is supposed to be. Read the guide again. There's a whole paragraph or two about it.


Quote:


Also, I have an LCD and at the 100% window, I get about 43 ftl, is it worth it to decrease contrast? If I do, the curve is not as straight but the avg. gamma may be closer (2.22 vs. 2.20?)

I don't know. Without seeing your viewing conditions and the size of the display and what sort of responses you're getting, it's impossible to say. If you're within the range I recommend in the guide and you're getting good numbers, and you're happy with the overall light output in your room then I'd say leave it along.

Again, 2.20 vs 2.22 gamma is so close that no human eye's going to notice the difference.

Quote:


Any advice on powersave and backlight options?

I don't follow.

Quote:


I was wondering, on the previous page here, whether or not you could use the same meathod to set contrast that you use to set brightness (relationship between 10 IRE and 100 IRE)

I don't know. I've never thought about it. Is there a reason you don't want to follow the method outlined in the guide?

Kal
post #158 of 258
Quote:
Originally Posted by kal View Post

2.20 and 2.22 are so close that frankly they're the same. I do talk in my guide as to what's the correct gamma and how people over the years have argued over what the correct gamma is supposed to be. Read the guide again. There's a whole paragraph or two about it.
Kal

-good to know, I wasn't sure how close they were. I did read the part about 2.2 vs. 2.5 controversy but I thought 2.2 was the accepted standard so I was curious to know if it was defined as 2.0 or 2.2.


Quote:
Originally Posted by kal View Post

I don't know. Without seeing your viewing conditions and the size of the display and what sort of responses you're getting, it's impossible to say. If you're within the range I recommend in the guide and you're getting good numbers, and you're happy with the overall light output in your room then I'd say leave it along.
Kal

-It seems that when I'm in the range of 30-40 it seems a bit dim during the day, but if I am above 40 it seems a bit too bright at night. I am leaning towards the brighter setting for all around viewing.

Quote:
Originally Posted by kal View Post

Again, 2.20 vs 2.22 gamma is so close that no human eye's going to notice the difference.


I don't follow.
Kal

- You seem to know more about projectors, but a lot of LCD displays have settings for backlight, including a power save option that decreases the overall light output by about half. I was just wondering how this differed from the Contrast setting and if it would be better to leave these backlight settings in the default position and set Contrast accordingly.


Quote:
Originally Posted by kal View Post

I don't know. I've never thought about it. Is there a reason you don't want to follow the method outlined in the guide?
Kal

- My only concern was that the range of 30-40 ftl seems rather large, so I was wondering if there was a more accurate way to set contrast. To me, 30ftl is significantly dimmer than 40ftl, so I don't know what to aim for. I'm currently getting 43ftl.
post #159 of 258
bummer! can't get to the page. Is the site down today?
post #160 of 258
Thread Starter 
Quote:
Originally Posted by vigilante1 View Post

-good to know, I wasn't sure how close they were. I did read the part about 2.2 vs. 2.5 controversy but I thought 2.2 was the accepted standard so I was curious to know if it was defined as 2.0 or 2.2.

You wrote 2.20 and 2.22 above. That's not the same as 2.0 and 2.2. That's a bigger difference. I did a lot of research into this and there's no 'correct' accepted standard it seems. It all depends.

Quote:


- You seem to know more about projectors, but a lot of LCD displays have settings for backlight, including a power save option that decreases the overall light output by about half. I was just wondering how this differed from the Contrast setting and if it would be better to leave these backlight settings in the default position and set Contrast accordingly.

Ah! Good question. I don't know. I'd leave it at default and see if you can get flat readings. If not you could try playing with both.

Quote:


- My only concern was that the range of 30-40 ftl seems rather large, so I was wondering if there was a more accurate way to set contrast. To me, 30ftl is significantly dimmer than 40ftl, so I don't know what to aim for. I'm currently getting 43ftl.

If your readings are good and you're not finding it over bright for your eyes in your viewing conditions then keep it how it is. There's no one correct number for the foot lambert output. That's why the guide gives ranges.

Kal
post #161 of 258
Thread Starter 
Quote:
Originally Posted by msvara View Post

bummer! can't get to the page. Is the site down today?

Was just down for 15 mins for a reboot.

Kal
post #162 of 258
My mistake, I did mean to type 2.20 and 2.22, I can't believe I typed 2.0 by mistake.

Thanks for the advice!
post #163 of 258
I am new to calibrating and had a general question.

I received an i1 LT yesterday and used this wonderful guide with the HCFR software to walk me through the basics. So far everything went rather well with my initial 'before' readings of my grayscale on my TC-P46G10, but I'm a bit confused about the gamma readings. I measured in my G10's THX mode and got an average of 2.08 which I know is a bit low for this picture mode--it should be spot on at 2.2. I followed this method from the guide to correct it:

Quote:


* Set the contrast as in the previous section and record the Y value (light output) on the 100 IRE window pattern.
* Display the 10 IRE window pattern.
* Adjust the brightness so that the Y reading of the 10 IRE window pattern measures as close as possible to 0.65% of the Y reading of the 100 IRE white pattern. For example: At 100 IRE we measured a Y value of 47.387. 0.65% of this is 47.387 x 0.0065, or a Y value of 0.308. We would therefore adjust the brightness until the Y value reads 0.308.
* This sets your gamma at 2.2 for the the 10 IRE window pattern which is typically the perfect gamma value as explained previously. In most cases this will be the correct setting for brightness. If your display has an unusually high or low gamma or a non-linear gamma, this method may give you the wrong result such that you can't see the 2% or 4% PLUGE bars (black clipping) or the black background is far too grey. In that case, adjust the brightness setting using the traditional method described previously using the PLUGE pattern.

After doing this my gamma was 2.2 but what I am confused about is I had to turn my contrast and brightness down to 58 and 48 respectively, which is quite lower than the settings they were at when I got the 2.08 gamma. I am not sure why I had to turn these settings down to get the gamma higher. Anyone care to explain?
post #164 of 258
Quote:
Originally Posted by Meteor|WAR View Post

After doing this my gamma was 2.2 but what I am confused about is I had to turn my contrast and brightness down to 58 and 48 respectively, which is quite lower than the settings they were at when I got the 2.08 gamma. I am not sure why I had to turn these settings down to get the gamma higher. Anyone care to explain?

What are your numbers for Y after turning the contrast and brightness to 58 and 48?

I actually forgot about this part when I did my Kuro 5020FD. Just looked at my report and my Ys are .2044 for 10 IRE and 36.4161 for 100 IRE. So ideally I suppose I should have 0.2367 for Y in 10 IRE, not sure if .03 difference matters.
post #165 of 258
Quote:
Originally Posted by jkcheng122 View Post

What are your numbers for Y after turning the contrast and brightness to 58 and 48?

I actually forgot about this part when I did my Kuro 5020FD. Just looked at my report and my Ys are .2044 for 10 IRE and 36.4161 for 100 IRE. So ideally I suppose I should have 0.2367 for Y in 10 IRE, not sure if .03 difference matters.

Unfortunately I am at work right now so I dont have that info. I can come back later and post it.

Are those numbers of your's for a projector? If I recall, I think my Y for 100 IRE was around 100. I will get back to you later on this.
post #166 of 258
My gamma is about 2.35. Is there a need to lower it to 2.2? How can I lower gamma?
Thank you!
post #167 of 258
Thread Starter 
Quote:
Originally Posted by hariskar View Post

My gamma is about 2.35. Is there a need to lower it to 2.2? How can I lower gamma?
Thank you!

How to add more gamma boost (ie: lower the gamma number) is explained in my guide. Here's a partial quote:

Quote:


Graph 2 - Gamma:

Gamma (or more accurately the gamma correction value) controls the overall brightness of an image or how fast the brightness curve comes out of black. The higher the gamma value the slower the signal comes out of black as the brightness increases. An average gamma value that is too high will result in a picture that is brighter with deeper blacks but also show less information in dark scenes. Our previous Luminance graph is proof of this. An average gamma value that is too low will produce an image that is less bright image with too much brightness in the dark scenes which gives a flat/washed out look.

Here is our graph of gamma from 0 to 100 IRE:



The target value for average gamma we are trying to achieve for our display is 2.2. The ColorHCFR software tries to target 2.2. The ideal target is to match a properly calibrated (telecine) mastering reference monitor used by the movie studios. These monitors are designed for a ruler flat 2.20 response.

A gamma value of 2.2 gives us a perfect balance: Plenty of brightness and excellent shadow detail. If your room is pitch black with very little light reflection and you have a display with a very high contrast ratio (such as a CRT projector) then you may find values up to as high as 2.5 to be acceptable (the debate of 2.2 vs 2.5 gamma is a huge raging debate amonst calibrators). In most cases however closer to 2.2 is likely going to look better and is what you should try and aim for. Remember that lower numbers mean more gamma/brightness. Later on when you remeasure your greyscale I'll suggest that you try and target 2.2. For what it's worth, I've tried both 2.5 and 2.2 and prefer something closer to 2.2 in my light controlled home theater powered by a CRT projector. If you have a means of adjusting gamma (see below), I recommend you try both and decide yourself. Either way you should not go over 2.5 or below 2.2.

A gamma that is too high like mine means that our overal brightness will be better and we'll have deeper blacks, but at the expense of losing details in the darker scenes. In our example, my gamma for each point from 0 to 100 IRE can be seen by the yellow line and ranges from something so high (beyond 3) it's off the graph, down to 2.27. The average gamma (cyan line) is 2.64 which is too high compared to the 2.2 target. The especially high values in the dark areas mean that in my setup I'm completely losing shadow detail which is typical of all CRT displays. This needs to be fixed by adjusting the gamma control within the display or by adding a a gamma boost box to the signal as most displays do not have an internal gamma adjustment option. (No CRT projector has the required type of gamma boost adjustment that we require built in).

As mentioned previously, I use an RTC2200 external box to add a gamma boost which helps me achieve the proper target numbers. This box as well as many high end scalers (Lumagen, Crystalio), Moome HDMI cards and converters, and the X-Vue Box1020, Box1021 and Box1040 RGB/Component converter products all have adjustable gamma boost features built in. If all you want is gamma boost in the least expensive package, then check out the GammaX dongle. It's designed by people behind the popular HDfury line of HDMI add-on converters.



Videophiles look for this gamma boost feature as it is a critical one to have in order to obtain a proper gamma curve. Without one of these devices in your signal chain, many displays will not track gamma properly and you'll end up with a dull/lifeless image with a lack of shadow details. More information on how gamma boost works and before & after screenshots showing why it's needed (especially on CRT displays) can be found in this thread:Gamma Correction: What is it? Why is it needed?

Later on we'll add the RTC2200 box back into the signal chain to see the difference it produces and explain how and when you should be adjusting your gamma (if you have such an adjustment available).

If your gamma is above 2.2 you'll want to look at adding one of these devices with adjustable gamma boost to your setup.

For more information on how to adjust gamma, why it means, an if it's required, read my Greyscale & Colour Calibration for Dummies guide.

Video processors often have gamma adjustments built in too. Then there's also the VideoEq. Some displays will also have gamma adjustments built in.

Kal
post #168 of 258
Thanx a freakin bunch for this!!!!!
I have calibrated my LG 2010 plasma with this and WOW times a million. What a difference!! And way to go LG for providing every single option without going into servicemenus . Glad i didn't buy another brand. Really great job with this guide. DIY ISF calibration!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!
post #169 of 258
Thread Starter 
Quote:
Originally Posted by rexblunt View Post

Thanx a freakin bunch for this!!!!!
I have calibrated my LG 2010 plasma with this and WOW times a million. What a difference!! And way to go LG for providing every single option without going into servicemenus . Glad i didn't buy another brand. Really great job with this guide. DIY ISF calibration!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!

You're welcome! I'm glad you liked my guide! Tell all your friends, call the neighbours, shout it from the rooftops!

Kal
post #170 of 258
Hi Kal,
Well I did tell my father in law and calibrated his set.
After that he said it was too yellow!
That's normal when you've watched 3 years of blue screen settings right?
Coz my new set looked fantastic.
I know i'm right right?
post #171 of 258
Thread Starter 
Quote:
Originally Posted by rexblunt View Post

Hi Kal,
Well I did tell my father in law and calibrated his set.
After that he said it was too yellow!
That's normal when you've watched 3 years of blue screen settings right?
Coz my new set looked fantastic.
I know i'm right right?

Post your graphs/results here and we'll have a look.
What meter are you using and how old is it?

Kal
post #172 of 258
Not sure if this is the best thread for it, but here goes. I recently bought a i1 Display Lt and calibrated my Mits WD-65738 with it using this guide with AVS HD709 and ColorHCFR. Everything adjusted smoothly and results seemed favorable with the exception of my secondaries. Took a snapshot for you to see. With my primaries as close as they are, my yellow and magenta Y values are way off. Yellow is 40% high, magenta is 30% low. Is there anyway to adjust this or is it just a product of the television? Thanks.
LL
post #173 of 258
Thread Starter 
Quote:
Originally Posted by Melonhead11 View Post

Not sure if this is the best thread for it, but here goes. I recently bought a i1 Display Lt and calibrated my Mits WD-65738 with it using this guide with AVS HD709 and ColorHCFR. Everything adjusted smoothly and results seemed favorable with the exception of my secondaries. Took a snapshot for you to see. With my primaries as close as they are, my yellow and magenta Y values are way off. Yellow is 40% high, magenta is 30% low. Is there anyway to adjust this or is it just a product of the television? Thanks.

Hi! You're probably best to ask in threads where people are talking about calibrating your particular TV to see if there's any adjustments that can be done for secondaries (since this is specific to your TV and not really related to the equipement or software you used to calibrate).

If you do not have primary/secondary adjustment in your TV (it's highly doubtful) then an external video processor could possibly be used too.

Kal
post #174 of 258
Quote:
Originally Posted by kal View Post

Hi! You're probably best to ask in threads where people are talking about calibrating your particular TV to see if there's any adjustments that can be done for secondaries (since this is specific to your TV and not really related to the equipement or software you used to calibrate).

If you do not have primary/secondary adjustment in your TV (it's highly doubtful) then an external video processor could possibly be used too.

Kal

It's a pretty new TV, so there isn't a thread yet. Maybe I'll start one. Primary/secondary has RGB adjustments, but it's not helping me much. Thanks.
post #175 of 258
Hi, With the JVC red is the color that gets weaker the fastest over time so I have to max red and make green and blue match red at 80 ire.

Now at 30 ire I can let red stay on 0 and again correct green and blue.

Question: Will this preserve the original gamma?

I mean I could also correct red and blue at 30 ire and keep green zero as is mentioned in the guide for crt beamers. But my feeling is that doing this will make the 80 ire pattern where I keep red zero diminish more relative than the 30 ire where I keep green zero. I think this would change the gamma from straight to something else?

Or does it not matter as long as I keep one color zero corrected to the original situation?

Any help appreciated.
post #176 of 258
Thread Starter 
Quote:
Originally Posted by redfox001 View Post

Question: Will this preserve the original gamma?

Best way is to measure it and see! Every display has different quirks so you sometimes just need to try it out and see what happens. I know I certainly did this a lot at first to get a 'feel' for how the display behaved.

Kal
post #177 of 258
Ok, and I just realized that if I correct brightness and contrast after the grayscale than the gamma should be ok?
post #178 of 258
Thread Starter 
Quote:
Originally Posted by redfox001 View Post

Ok, and I just realized that if I correct brightness and contrast after the grayscale than the gamma should be ok?

Any time you make any adjustments you should always go through another quick measurement of everything to make sure that other factors aren't affected.

As soon as you make it through a run of complete measurements without adjusting anything, you're done.

Kal
post #179 of 258
Thanks! Sometimes I can get very confused but just following the guide will take me home
post #180 of 258
Hi kal! first I want to say thanks for the guide. now, for you or anybody that can help. I calibrated my lg55wl5600 last night(or should I say am trying) here are my graphs. I think everything is ok, but am curious if it is normal for the 0 ire to always be way off in the delta-e value. also my cie trianle does not line up(I have no idea what that means) I have only done greyscale and not color calibrations. any help would be appreciated!!!!
LL
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LL
LL
LL
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