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diff --git a/doc/i1proDriver.html b/doc/i1proDriver.html index 0894f59..e29d639 100644 --- a/doc/i1proDriver.html +++ b/doc/i1proDriver.html @@ -1,157 +1,195 @@ <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> -<head> - <title>The i1pro Driver</title> - <meta http-equiv="content-type" - content="text/html; charset=ISO-8859-1"> - <meta content="Graeme Gill" name="author"> -</head> -<body> -<h2 style="text-decoration: underline; font-weight: bold;">How can I -have confidence in the i1pro Driver ?<br> -</h2> -A question that has been asked is : "<span style="font-weight: bold;">You've -written your own driver for the Eye-One Pro. How can I have confidence -that the measurements are accurate, and will match those made with the -original manufacturers driver </span>?"<br> -<br> -This is a quite reasonable question. The following attempts to answer -it.<br> -<h4 style="text-decoration: underline;">Why does Argyll use it's own -i1pro driver ?</h4> -Primarily because the Original Manufacturers Driver (OMD) isn't -available for all the platforms that ArgyllCMS supports (Linux in -particular). A side benefit is that it's possible to tweak many of the -driver parameters for slightly better results and more flexibility. It -has also helped in understanding the characteristics and limitations of -such instruments.<br> -<h4 style="text-decoration: underline;">Does it match the OMD ?</h4> -In principle the behaviour should be very similar. While the Argyll -driver has been written from scratch, it does use exactly the same -calibration values from<br> -inside the instrument, and attempts to use the calibration values and -process the raw instrument readings in an equivalent manner to that of -the OMD.<br> -<br> -But the proof of the pudding is in the measuring, so to actually verify -this, the following experiment was conducted:<br> -<br> -The Argyll version used was V1.2.0<br> -<br> -The Macbeth 24 patch ColorChecker was used as a sample target. For each -patch (and the calibration tile), the following steps were performed:<br> -<br> -1) Place the instrument on the calibration tile.<br> -<br> -2) Use Argyll spotread to calibrate the Argyll driver.<br> -<br> -3) Change drivers to the OMD.<br> -<br> -4) Use the OMD to calibrate the instrument.<br> -<br> -5) Move the instrument to the patch on the ColorChecker.<br> -<br> -6) Read the color using the OMD.<br> -<br> -7) Change the back to the Argyll driver.<br> -<br> -8) Using the calibration made in step 2), read the color using Argyll.<br> -<br> -Each calibration or reading was performed 15 seconds from the previous -one, to put the instrument lamp in a repeatable state.<br> -The instrument was kept in exactly the same position for calibration -and patch measurement with the two drivers.<br> -(The whole idea is to reduce all other sources of error, other than the -driver itself.)<br> -<br> -This measurement was repeated just once for each patch + the -calibration tile. This was done in one run, and the readings were not -specially selected.<br> -<h4 style="text-decoration: underline;">Results:</h4> -The following D50 L*a*b* values were recorded for each measurement:<br> -<br> -A) The OMD internally calculated L*a*b* value<br> -B) The L*a*b* value calculated by Argyll from the OMD -spectral values.<br> -C) The L*a*b* value calculated from the Argyll measured -spectral values.<br> -D) The L*a*b* value calculated from the Argyll -Hi-Resolution mode measured spectral values.<br> -<br> -<span style="text-decoration: underline;">A is compare to B, to check -that the spectral to standard observer calculations are equivalent.</span><br> -<br> - The result was an average Delta E (CIE76) of 0.006, -with a maximum of 0.012.<br> -<br> - This shows that there is very close agreement in the -way spectral values are converted to XYZ and L*a*b*.<br> -<br> -<span style="text-decoration: underline;">B is compared to C to check -that the Argyll driver behaves the same as the OMD.</span><br> -<br> - The result was an average Delta E (CIE76) of 0.028, -with a maximum of 0.051.<br> -<br> - This shows that the OMD and Argyll driver are in -close agreement in spectral measurement.<br> - This error is an order of magnitude smaller than -uniformity induced errors typical in the media being measured.<br> -<br> -<span style="text-decoration: underline;">A is compared to C to check -that the Argyll driver and spectral to XYZ differences don't compound.</span><br> -<br> - The result was an <span style="font-weight: bold;">average</span> -Delta E (CIE76) of <span style="font-weight: bold;">0.026</span>, with -a <span style="font-weight: bold;">maximum</span> of <span - style="font-weight: bold;">0.048</span>.<br> -<br> - Rather than compounding, any spectral to XYZ -differences tend to cancel -out slightly. This is the <span style="font-weight: bold;">bottom line</span> -experimental difference between -the two drivers. The actual underlying difference may in fact be less -than this, but it would be necessary to do multiple test runs to -filter out experimental error.<br> -<br> -<span style="text-decoration: underline;">C is compare to D to check -that the Argyll Hi-Resolution mode is behaving reasonably.</span><br> -<br> - The result was an average Delta E (CIE76) of 0.158, -with a maximum of 0.353.<br> -<br> - Because the ColorChecker samples have relatively -smooth reflectance spectra, it can be expected that<br> - the normal and Hi-Res mode results should be fairly -similar. And indeed, this is the case. The biggest<br> - differences are for patches -with the largest spectral transitions in them, which is to be expected -as the<br> - Hi-Res measurement more -closely follows the spectral shape, while the differences for -spectrally flat<br> - patches is neglegable, since both can follow the -spectral shape well.<br> -<br> -Example Yellow-Green Patch, Hi-Res & Normal spectrum:<br> -<img style="width: 709px; height: 259px;" - alt="Yellow-Green patch, Hi-Res vs. Normal" src="YellowGreen.jpg"><br> -<br> -<h4 style="text-decoration: underline;">Conclusions:</h4> -The experimental average difference of <span style="font-weight: bold;">0.026</span> -Delta E76 shown above provides evidence that despite using a completely -different instrument driver to that supplied with the instrument, the -ArgyllCMS Eye-One pro measurement values have comparable accuracy, and -can be relied upon to match measurements made using the original -manufactures driver.<br> -<h4 style="text-decoration: underline;">Raw Data:</h4> -The raw data is available in this <a href="i1proDriver.xls">spread -sheet</a>.<br> -<br> -<br> -<br> -<br> -<br> -<br> -</body> + <head> + <title>The i1pro Driver</title> + <meta http-equiv="content-type" content="text/html; + charset=windows-1252"> + <meta content="Graeme Gill" name="author"> + </head> + <body> + <h2 style="text-decoration: underline; font-weight: bold;">How can I + have confidence in the i1pro Driver ?<br> + </h2> + A question that has been asked is : "<span style="font-weight: + bold;">You've + written your own driver for the Eye-One Pro. How can I have + confidence + that the measurements are accurate, and will match those made with + the + original manufacturers driver </span>?"<br> + <br> + This is a quite reasonable question. The following attempts to + answer + it.<br> + <h4 style="text-decoration: underline;">Why does Argyll use it's own + i1pro driver ?</h4> + Primarily because the Original Manufacturers Driver (OMD) isn't + available for all the platforms that ArgyllCMS supports (Linux in + particular). A side benefit is that it's possible to tweak many of + the + driver parameters for slightly better results and more flexibility. + It + has also helped in understanding the characteristics and limitations + of + such instruments.<br> + <h4 style="text-decoration: underline;">Does it match the OMD ?</h4> + In principle the behaviour should be very similar. While the Argyll + driver has been written from scratch, it does use exactly the same + calibration values from<br> + inside the instrument, and attempts to use the calibration values + and + process the raw instrument readings in an equivalent manner to that + of + the OMD.<br> + <br> + But the proof of the pudding is in the measuring, so to actually + verify + this, the following experiment was conducted:<br> + <br> + The Argyll version used was V1.2.0<br> + The OMD is the original version prior to the introduction of the + i1pro2, and hence reporting the native instrument measurements, + rather than applying a conversion to the XRGA standard<br> + <br> + The Macbeth 24 patch ColorChecker was used as a sample target. For + each + patch (and the calibration tile), the following steps were + performed:<br> + <br> + 1) Place the instrument on the calibration tile.<br> + <br> + 2) Use Argyll spotread to calibrate the Argyll driver.<br> + <br> + 3) Change drivers to the OMD.<br> + <br> + 4) Use the OMD to calibrate the instrument.<br> + <br> + 5) Move the instrument to the patch on the ColorChecker.<br> + <br> + 6) Read the color using the OMD.<br> + <br> + 7) Change the back to the Argyll driver.<br> + <br> + 8) Using the calibration made in step 2), read the color using + Argyll.<br> + <br> + Each calibration or reading was performed 15 seconds from the + previous + one, to put the instrument lamp in a repeatable state.<br> + The instrument was kept in exactly the same position for calibration + and patch measurement with the two drivers.<br> + (The whole idea is to reduce all other sources of error, other than + the + driver itself.)<br> + <br> + This measurement was repeated just once for each patch + the + calibration tile. This was done in one run, and the readings were + not + specially selected.<br> + <h4 style="text-decoration: underline;">Results:</h4> + The following D50 L*a*b* values were recorded for each measurement:<br> + <br> + A) The OMD internally calculated L*a*b* value<br> + B) The L*a*b* value calculated by Argyll from the OMD + spectral values.<br> + C) The L*a*b* value calculated from the Argyll measured + spectral values.<br> + D) The L*a*b* value calculated from the Argyll + Hi-Resolution mode measured spectral values.<br> + <br> + <span style="text-decoration: underline;">A is compare to B, to + check + that the spectral to standard observer calculations are + equivalent.</span><br> + <br> + The result was an average Delta E (CIE76) of + 0.006, + with a maximum of 0.012.<br> + <br> + This shows that there is very close agreement in + the + way spectral values are converted to XYZ and L*a*b*.<br> + <br> + <span style="text-decoration: underline;">B is compared to C to + check + that the Argyll driver behaves the same as the OMD.</span><br> + <br> + The result was an average Delta E (CIE76) of + 0.028, + with a maximum of 0.051.<br> + <br> + This shows that the OMD and Argyll driver are in + close agreement in spectral measurement.<br> + This error is an order of magnitude smaller than + uniformity induced errors typical in the media being measured.<br> + <br> + <span style="text-decoration: underline;">A is compared to C to + check + that the Argyll driver and spectral to XYZ differences don't + compound.</span><br> + <br> + The result was an <span style="font-weight: + bold;">average</span> + Delta E (CIE76) of <span style="font-weight: bold;">0.026</span>, + with + a <span style="font-weight: bold;">maximum</span> of <span + style="font-weight: bold;">0.048</span>.<br> + <br> + Rather than compounding, any spectral to XYZ + differences tend to cancel + out slightly. This is the <span style="font-weight: bold;">bottom + line</span> + experimental difference between + the two drivers. The actual underlying difference may in fact be + less + than this, but it would be necessary to do multiple test runs to + filter out experimental error.<br> + <br> + <span style="text-decoration: underline;">C is compare to D to check + that the Argyll Hi-Resolution mode is behaving reasonably.</span><br> + <br> + The result was an average Delta E (CIE76) of + 0.158, + with a maximum of 0.353.<br> + <br> + Because the ColorChecker samples have relatively + smooth reflectance spectra, it can be expected that<br> + the normal and Hi-Res mode results should be + fairly + similar. And indeed, this is the case. The biggest<br> + differences are for patches + with the largest spectral transitions in them, which is to be + expected + as the<br> + Hi-Res measurement more + closely follows the spectral shape, while the differences for + spectrally flat<br> + patches is neglegable, since both can follow the + spectral shape well.<br> + <br> + Example Yellow-Green Patch, Hi-Res & Normal spectrum:<br> + <img style="width: 709px; height: 259px;" alt="Yellow-Green patch, + Hi-Res vs. Normal" src="YellowGreen.jpg"><br> + <br> + <h4 style="text-decoration: underline;">Conclusions:</h4> + The experimental average difference of <span style="font-weight: + bold;">0.026</span> + Delta E76 shown above provides evidence that despite using a + completely + different instrument driver to that supplied with the instrument, + the + ArgyllCMS Eye-One pro measurement values have comparable accuracy, + and + can be relied upon to match measurements made using the original + manufactures driver.<br> + <h4 style="text-decoration: underline;">Raw Data:</h4> + The raw data is available in this <a href="i1proDriver.xls">spread + sheet</a>.<br> + <br> + <br> + <br> + <br> + <br> + <br> + </body> </html> |