REVIEW: Samsung 245B Part 12

Comparison of MagicColor with sRGB standard

Factory setting	Manufacturer	Measured
White point / Kelvin	No details	6600
Brightness / cd/m²	400	388
Black point / cd/m²	No details	0,39
Gamma / Average	No details	2,59
Contrast / x:1	1000	994

When calibrating to sRGB we came across a problem on the first Samsung 245B test model: Either the pixel control or background lighting or both do not function precisely enough for calibration: When set to an exact brightness value, the brightness sinks continually within the next 10-20 minutes by 20-25 cd/m². Hours later, the brightness has then reached its previous value.

This makes sensible calibration practically impossible: Either you calibrate to around 120 cd/m² in order to effectively reach 140 cd/m² later or you calibrate to 140 cd/m² and have a brightness of 160 cd/m² hours later. In both cases, the RGB colours which depend on the brightness cannot be set precisely enough, and so we had to go through seven detailed calibration processes simply to find out with which OSD brightness settings we could achieve "the next best thing".

Comparison of the calibrated profile with sRGB

Calibrated	Target	Measured
White point / Kelvin	6500	6600
Brightness / cd/m²	140	137
Black point / cd/m²	0,00	0,18
Gamma / Average	sRGB (~2,2)	2,17
Contrast	Native	760

We achieved the above results with the following settings: contrast 50, gamma mode 1, brightness 74, red 49, green 43, blue 52; the MagicColor function must be deactivated. As can be seen in the diagram, the grey levels are very good after calibration and even dark levels are almost completely displayed. Those deviations in colour still present are a result of the fact that the SyncMaster 245B does not completely cover the sRGB colour space, as visible in the colour comparisons above.

It is obvious how much the brightness drops from the fact that this sank by 3 cd/m² to 137 cd/m² within the short time it took to calibrate the monitor. 24 hours later, the brightness is 158 cd/m², the gamma value has fallen to 2.01 and the contrast has dropped as a result. Eventually, the required 140 cd/m² was achieved with a brightness value of 62 and slightly corrected RGB values of R50, G43 and B51.

Deviation of the calibrated profile 24 hours after calibration

Calibrated	Target	Measured
White point / Kelvin	6500	6600
Brightness / cd/m²	140	158
Black point / cd/m²	0,00	0,40
Gamma / Average	sRGB (~2,2)	2,01
Contrast / x:1	Nativ	394

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