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Panasonic PT-RZ670BU Projector Review - Picture Quality

Posted on December 1, 2014 by Jarrod Buckley
PANASONIC PT-RZ670BU PROJECTOR:  Picture Mode, Picture Quality, Image Quality with Text

Picture Modes

The PT-RZ670BU offers 7 different Picture Modes.  The photos above show our standard color wheel test image displayed with each of these picture modes and with the projector's default settings.  It was interesting that even the brightest mode (i.e., Dynamic) produced reasonably good color accuracy.  This is rather unusual as most business-class projector's will typically have a rather blue (or blue-green) overall tint and a very high color temperature (e.g., 9000K or higher) in brightest mode.   Generally, such modes are useful only in the most extreme cases where maximum light output is need to overcome bright ambient light conditions.  This is simply not the case with the PT-RZ670BU where the dynamic mode color temperature measured about 7000K and was fairly uniform across the grey scale.  Not that colors were perfect in this mode, but the dynamic picture mode is very usable on this projector when you really need high brightness.  I would note that in Dynamic Picture mode, with it default high setting for "white gain", the brightness of whites and bright greys were exaggerated as compared to the full color portions of the image.

Of the picture modes available the Standard mode had the best out of the box grey scale with a color temperature within a couple hundred degrees of the reference 6500K used for video, but several of the modes could be calibrated for accurate grey scale with a little effort.  While we do not normally attempt to calibrate business and education class projectors that we review. I did do a check of the grey scale/color temp accuracy in each of the projector's 7 picture mode then adjusted the grey scale for the Rec709 mode using just the projector's White Balance high and low adjustments for red, blue and green primary colors.  The two images below show the before and after results from these adjustments.

BEFORE:  with factory default settings

BEFORE: with factory default settings

AFTER:  with white balance adjustments

AFTER: with adjustments

For those interested in the white balance settings I used for the After results above, these are summarized below:

While Balance - High

Red = +244

Green = +252

Blue = +255

 While Balance - Low

Red = -4

Green = -2

Blue = +1

The other picture setting I used for my simple calibration are summarized below:

Contrast = -2

Brightness = +1

Color = 0

Tint = 0

White Gain = 0

Gamma = 2.2

Daylight View = OFF

Sharpness = 0

System Daylight View = OFF

Noise Reduction = OFF

Dynamic Contrast = OFF (set to a value of 1 after calibration)

I did not attempt to calibrate the projector's color gamut.  While the primary color's saturation and hue  were fairly accurate in just about all of the picture modes,  I noted that the brightness of individual colors did appear too low, or occasionally too high with all of the picture modes.  This should be able to be corrected by using the projector's available adjustments.

Picture Quality

The above photos are scenes from Casino Royale that were taken with the projector in the Rec709 picture mode with the factory default settings.  Flesh tones looked natural, but just a little on the too warm side, and  colors were good as seen in the first photo above.   In terms of color accuracy the Rec709 mode was fairly accurate with the yellows being a little over saturated and the blues being a little under saturated.

As for some of the other Picture Modes, Dynamic had red and yellow colors a little over saturated while the biggest color errors in Dynamic mode were for cyan and magenta colors which were shift substantially toward blue.  In Dynamic mode with is high default setting for White Gain, the white and bright grey picture elements appears somewhat unnaturally bright as compared to the full color picture elements.   Even so, videos were certainly watchable in dynamic mode, even without ideal color accuracy.

Standard Picture mode had fairly good out the box colors and good grey scale tracking.  While all of the colors had reasonably good saturation and hue accuracy, they were all a little too dark as compared to the white,  from what is considered ideal.   The gamma for the mode was not very constant which resulted in the image have less apparent contrast than some other modes.  However, the Standard mode works fairly well for displaying video.

Cinema picture mode appeared too warm indicating a lower than desired color temperature.  As with Standard mode, the less than ideal gamma resulted in an image with less apparent contrast than in some other modes.  The color accuracy was similar to Rec709 mode except the whites were shifted toward yellow.

DICOM Sim. mode is intended for displaying black and white images and thus color accuracy is not of concern, but having reasonable grey scale tracking with uniform color temperature is desirable.  The PT-RZ670BU performed well in this regard with the color temperature remaining close to 7200K across the grey scale.

Virtually all of the above Picture Modes, as well as those not specifically discussed, could be improved via a professional calibration using the projector's extensive calibration adjusts.

I would rate this projector as having moderate contrast performance.  Certainly better than typical LCD business class projectors.  The projector has a dynamic contrast adjustment, but when viewing video I found that setting this control higher than the lowest setting produced noticeable black level pumping as the overall image brightness was increased and decreased based on changes in the video program material.   The 2nd of the above photos shows the night train scene from the Casino Royale movie and this photo was intentionally over exposed  to show the dark details within the image.  The results are good for this class of projector but certainly below that possible with high contrast projectors (including many home theater class DLP projectors).  Image sharpness was excellent, as it typical for single-chip DLP 1080p projectors.  While this projector has 1920 x 1200 native resolution, when displaying HD video, with its 16 x 9 aspect ratio, the displayed image it limited to 1920 x 1080 (i.e., full 1080p HD).

I do believe that a professional calibration of this projector could produce excellent accuracy for grey scale, gamut and gamma.  While the projector's black levels and contrast ratio are only moderate, given this model is not being marketed for use in a dark theater-like environment, its performance in these areas if far more than adequate for its intended use, i.e., where some ambient lighting is expected.

All single chip DLP projectors have the potential to display color separation artifacts, commonly called Rainbow Effect (RBE).  The faster the projector displays the sequence of the single color sub-images (at least Red, Blue and Green sub-images), then the less likely viewers will see any RBE.  A projector that displays each of the primary color sub-images just one time each 1/60 second is referred to has having 1X speed.  If it displays two complete sets of sub-images each 1/60 sec.. it said to be 2x speed.  Generally most viewers will only occasionally notice RBE when the speed is gets up 3X and as you move up to speeds of 5X and 6X very few viewers will never notice RBE.  Panasonic does not specify this speed for the PT-RZ670BU, so I went ahead and measured it with a 60Hz video signal input and determined it is 3X and yes, I could occasionally see RBE when viewing video content (especially high contrast images).  Note that some people are very sensitive to RBE while others do not notice it even with DL projectors having 2X speed.  The bottom line is the PT-RZ670BU, with its 3X speed, is it fast enough for its intended primary use.

Image Sharpness with Text

PT-RZ670B Text-1 Pic

As can be seen in the photo above and the two closer-up photos below, the PT-RZ670BU produces sharp, clear text and it well suited for presentations of text, diagrams or graphics such as are used with business presentations.

PT-RZ670B Text-2 Pic

PT-RZ670B Text-3 Pic

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