My Workflow - Samsung LCD with DTP94 & HCFR - AVS Forum
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post #1 of 6 Old 07-20-2010, 02:28 PM - Thread Starter
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Hi everyone!

I've been calibrating my home computer displays for years with my DTP94 device. My other hobby is digital photography, and I've always been a color nerd.

I recently purchased a Samsung LCD TV (LN46C630), and while I was blown away with the picture quality, I could see that the colors were inaccurate, the white balance was funky, and the blacks and whites never seemed to be quite right.

I started reading about calibration, and soon realized that my DTP94 device I'd been using all these years, could be used with a free software (HCFR)!

I've spent the last few weeks reading and testing and tweaking in my spare time, and developed a work-flow that works for me. I've read many guides, and none have been exactly what I needed, so I decided to share it with the internet, maybe someone will find this useful. I'd also like feedback and critique, as I'm sure I am wrong in many ways.

Useful Links:
Chapter 1 - Visual Calibration
It really helps to start out with a visual calibration. This gets your set in the ballpark, and makes the next steps much easier. Think of the visual calibration as a coarse knob and the DTP94 calibration as the fine tune knob.

I have my set hooked to a HTPC, but it doesn't really matter your source. Just make sure the HDMI black levels are the same on the set and your source. For most situations, this should be set at "limited" or "low" or "16-235." Turn off any settings that dynamically adjust the picture.

For my set (LN46C630), I started with the following settings:
  • Movie Mode
  • Backlight - between 4 and 6
  • Sharpness - 0
  • Eco Sensor - off
  • Energy Saving - off
  • Black Tone - off
  • Dynamic - off
  • Shadow Detail - 0
  • Gamma - 0
  • Color Space - Custom, and leave at the defaults for now.
  • White Balance - Leave at default for now.
  • 10pt White Balance - On and leave at default for now.
  • Flesh Tone - Off
  • Edge Enhancement - Off
  • Color Tone - Warm2
  • HDMI Black Level - Low (Unless you are using a HTPC and know what you are doing.)
  • Auto Motion Plus - Off (my preference, it doesn't affect calibration as far as I can tell)
  • Digital Noise Filter - Off
  • MPEG Noise Filter - Off

Let your set warm up for 30 minutes or so.

Pop in the AVS-HD disc, or load up the files on your HTPC.

Chapter 1 and 2: Brightness - Black Level:
From the AVS-HD manual:
Quote:


Set the brightness control to the lowest setting where the bars numbered 17-25 flash. For chapter 2 it may be more difficult to see 17 flash, and we suggest setting brightness no lower than where 19-25 flash. Many displays can use a similar brightness setting for chapters 1 and 2, but use the higher setting if results differ significantly.

We're trying to get a level where the darkest blacks are able to be distinguished from the absolute black. No blacks should be clipped. If you need to adjust the backlight to achieve that, do so.

Chapter 2 and 3 - Contrast - White Level:
From the AVS-HD manual:
Quote:


Look at chapters 2 and 3. Generally set the contrast control as high as possible, so long as most all the bars numbered 230-253 flash. For a less-conservative approach, or for displays that do not display 235-253, flashing bars 230-234 is also acceptable. You may also want to look at items such as color shift or eyestrain, which are mentioned in the White Clipping Pattern description.

With my set, I was only able to get bars 230-234 to flash. You will probably have to adjust the backlight to get this right. It is very important that you are not clipping whites here.

Chapter 4 - Color Bars

My set has a blue filter, but if yours does not, you can purchase blue filter glasses online.

For my set, turn "RGB only mode" to "Blue"

Looking at the flashing color bars through a blue filter, adjust the "color" setting so that the flashing bars on the far right and far left are the same as the boxes within. Get them as close as possible, ideally so you don't see them flash at all.

Once you have that dialed in, adjust the "Tint" control until the middle two bars match the boxes within, as you just did with the color bars above.

When this is dialed in, switch off the blue filter.

Chapter A2 - Grayscale Step
I like to double check using a grayscale step pattern. Check each bar on both steps, to make sure that each bar is distinguishable from the bar next to it. The last 2 white and black bars should be indistinguishable from each other. If you are clipping whites, go back to chapter 2 and 3 and adjust the white level (contrast). If you are clipping blacks, go back to chapter 1 and 2 and adjust the black level (brightness).

Inspection:
Pop in a nice 1080p movie. Skip around and pay close attention to shadows and bright spots. Make sure information isn't being clipped or lost. Colors aren't going to be spot on, yet, but you're mostly checking to make sure things are closer than before.


Chapter 2 - Setting up the DTP94

We're now going to be hooking up the DTP94. It really helps to have a laptop at this point, but you can do this with a desktop if you don't mind hooking it up next to your set.

Setting up HCFR with the DTP94 is pretty easy, but has a few obscure steps.
Here's how I did it, on Windows 7 32bit:
  1. Download HCFR and install.
  2. Download the drivers for the DTP94 from Calman. It's called "Device Driver Kit"
  3. Install the Driver Kit.
  4. Plug in the DTP94. Windows will not be able to install the drivers, so point windows to the "C:\\Program Files\\SpectraCal\\Drivers\\DTP94" folder.
  5. Download "XdsIII.dll" Extract the .dll file to "C:\\Program Files\\ColorHCFR"

Once you're all set-up, make sure the set has been warmed up. A lot of guides tell you to warm up the colorimeter while attached to the TV.

In the HCFR program, click "Advanced" -> "Preferences" then click on the "References" tab. Select "HDTV - REC 709" in the color space box.

Click "File" -> "New" to start a new test. Under "generator selection" choose "DVD Manual." Pick "DTP94" in the next box. Click finish.

Now we'll calibrate the sensor. Click "Measures" -> "Sensor" -> "Configure." Check "Average reads on dark measurements" then place the sensor face down on a black, non-reflective surface, in as dark of a room as you can get. I use the inside of a DVD case. Click "Measure internal offsets" and let it do its thing. Press OK.

In the Main Screen, under "Display" check "xyY." We'll be using that method to measure color and illumination.

Chapter 3 - Taking a Reference Measurement

Pop in the AVS-HD disc and queue up the "ColorHCFR Windows" "10% Grayscale" chapter. This test displays an absolute black background, with a box inside, stepping up from 0APL to 110APL. We're only concerned with 1-100APL.

Position the DTP94 so it is laying gently and flat against the middle of the screen, where the grayscale box is displayed. If you are using a HTPC, make sure the seek bar and mouse pointer has disappeared before you measure.

Click on the "measure grayscale and primaries and secondaries" button and run through the 0% to 100% as indicated. 0% will take some time to complete, as much as a minute, but as you increase in lightness, the measure times will decrease.

When it gets to "Red" go to "100% Color Windowed" in AVS-HD, and run through red-green-blue-yellow-magenta-cyan-white, as indicated.

When it finishes measuring, save the file. Save it with "before" in the filename so you know its a reference measurement, ie "LCD_before."

At this point, you can look at the graphs to see how far off you are from reference. Graphs are found in the "graphs" menu. The useful ones as of now, are "Luminance" "Gamma" and "RGB Levels"

At this point there is no reason for me to re-invent the wheel. Read up "Part 2.3: Graphs" at curtpalme, for a better explanation of the graphs.

Chapter 4 - Setting White and Black levels with the DTP94

Start a new measure file in HCFR and save it as before, but with "after." ie LCD_after"

White Level:
In AVS-HD, display a 100% white windowed pattern. With the DTP94 in place on the screen, click the green arrow button "Continuous Measure." This will measure continuously and display the results under the "data" table.

Your white level should be about right at this point, but if it is above 50ftL (for LCDs), you need to decrease your backlight levels and re-run the tests in Chapter 1 of this guide.

Take note of the "Y" value at this point. We'll need it for the next step.

Black Level:
Take the "Y" value above and multiply it by 0.006. (ie if we measured 45.25, then it would be 45.25 * .006 = .2715)

Display a 10% gray box, windowed. Click "Continuous Measure" and check your new "Y" value. You should be very close to your above calculated value. Adjust your "Brightness" setting to get as close as you can to that value. If you have to adjust more than a few ticks, you are probably clipping blacks, and you need to go back to chapter 1 of this guide, and get closer. This step is for fine tuning only.

Chapter 5 - Setting the Color and Tint using the DTP94

As above, we're going to be just fine tuning the color and tint settings. If you have to adjust them more than a few ticks, you're probably going to need to re-do them visually, first.

Display a 100% white box windowed, and measure the "Y" value. Multiply that value by .20 to get a new "Y" value.
Display a 100% red box windowed, and adjust the "color" setting until your "Y" value is as close to that result calculated above.

I didn't adjust the tint using the colorimeter, but Tom Huffman shows you how here.

Chapter 6 - Adjusting the Grayscale using the DTP94

I'm going to assume you already know what grayscale is at this point. If not, read up here and here.

80/20 White Balance:
We'll start by adjusting the "White Balance" settings. On the LN46C630, and similar sets with a 10 point white balance, the "White Balance" is the coarse knob, and the "10pt white balance" is the fine tune knob. We'll get the "White Balance" as close as we can, then we'll mess with the "10pt white balance"

Display a 80% gray box windowed, and start taking continuous readings with the DTP94 in place. Adjust the "Red Gain" and "Blue Gain" (do not adjust the green gain) until the three bars in HCFR under "RGB Levels" are as close to 100% as possible.

Now display a 20% gray box windowed, and do as above, but adjusting the "Red Offset" and "Blue Offset" (do not adjust the green offset). Remember to be patient, as a 20% gray box will take time for the sensor to read. Give it 2 readings before making adjustments.

Now go back and adjust the 80% again, as it has likely changed. Repeat the 20% as well.

You should be getting in the ballpark at this point. You can take a grayscale measure at this point for fun if you'd like. You're probably getting very close to reference.

10 point white balance:
Now we're going to do exactly as above, but for every 10% level.

Start by displaying a 10% gray box, windowed. Set the 10pt white balance interval to "1." Adjust as above, getting the color bars as close to 100% as possible, adjusting ONLY RED AND BLUE.

Repeat for every step. 1=10% 2=20%...10=100%

Once you've gone through, start over and adjust each step again, as every setting affects each other.

Chapter 7 - Color Settings Using the CMS

This chapter is a work in progress, as I'm still refining my skills here.

Some notes from Tom Huffman
Quote:


The Samsungs use a color mixing strategy that works very well.

* To desaturate a primary, add equal amounts of both of the other 2 primaries to it. To desaturate a secondary, add the opposing primary to it.
* To change the hue of a primary add unequal amounts of the other 2 primaries. To change the hue of a secondary, add unequal amounts of the contributing primaries.
* To decrease the lightness of a primary, reduce the amount of the primary itself. To decrease the lightness of a secondary, decrease equally the amount of the contributing primaries.

You cannot increase saturation or lightness.

Great Calculation Spreadsheets

Chapter 8 - Comparison

Now we're going to Measure "Grayscale primaries and secondaries" as in chapter 3.

After doing so, save the file, (ie LCD_after) and open your Reference measurement file (ie, LCD_before) as well. Under "Parameters" click "Reference Measurement" in the "_before" file.

Now, view the graphs in the "_after" file, and you will see your reference measurements plotted alongside your final measurements. Hopefully you see a great improvement!
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post #2 of 6 Old 07-20-2010, 02:28 PM - Thread Starter
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Please note: this is a work in progress, and I'm looking for feedback. I don't pretend to know everything about this process, I'm just trying to share what I DO know with others, while learning myself.

Please feel free to tell me I'm wrong, rip me apart, etc. I love constructive criticism!
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post #3 of 6 Old 07-21-2010, 07:18 PM
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Not really good to set black level using this multiplication method as a general rule. Any given multiplier only applies to a given gamma, and the proper gamma depends on the viewing environment.

Much better to stick to setting black level with the pluge style patterns, and then tweak gamma if there's not enough shadow detail.

-Greg
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post #4 of 6 Old 09-07-2010, 06:15 AM
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Hi Cheezerman,
I just bought a Samsung LE46c630 (In think that LE is the European version of the LN but I am not sure) and I am not happy with picture settings.
Please, can you post the settings that you obtained according to the calibration you have made ? I would be glad to try them.
Thank you very much in advance !
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post #5 of 6 Old 09-09-2010, 08:17 AM
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post #6 of 6 Old 09-10-2010, 02:09 AM
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Thanks !
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