Measurement test of Sapp WX450 ST projector: better picture and better health!

* VISUAL TEST * CANON

Test projector Sapp WX450 ST: better picture, better health! Experts believe that Canon is one of the top three projectors with LCoS technology. And in the multimedia segment it occupies a leading position, mastering new areas of application of projection technology, for example, in medical centers – for therapeutic purposes. Truly, a better picture is better health! So we decided to test strictly and independently one of the latest multimedia novelties – projector Saps WX450 ST. I wonder how the test results will affect our health?

Sapp WX450 ST Multimedia Projector

Test methodology

Testing of Sapp WX450 ST projector was conducted in our office. The image was displayed on the SCREEN MARK from a distance of 1.5 meters. Measured with X-Rite i1Display Pro colorimeter.

The software used was the freeware HCFR Colorimeter 3.1.0.6. This program understands the correction profiles supplied by the colorimeter manufacturer.Spectral correction profiles are designed to increase measurement accuracy – due to corrections in the results of measurements, which were made depending on the type of backlighting of the display device CRT, CCFL, W-LED, Wide Gamut, Projector and others .

In our case, the only choice is the profile designed to measure projectors. We’ve tested all of the projector’s Standard, Presentation, Photo/sRGB, DICOM SIM modes. We were interested in the main parameters that affect image quality:

• Uniformity of screen illumination
• Color Gamut
• Contrast
• Gamma Curve
• Grayscale
• Color accuracy
• Color temperature stability

Selected mode, look and lie

Every mode in a projector is designed for something. As you name it, so it will show – according to the name, each of them will have its own image quality requirements. The Sapp WX450 ST has four factory preset modes:

Standard mode – here it’s up to the manufacturer.

Presentation mode – the brightness and contrast are of prime importance here, for excellent readability of text, graphics, etc. in all conditions. Movie theater requirements for color temperature and color tones are not normally met here.

Photo/sRGB mode – usually this mode has pretty precise image settings, allowing you to enjoy close-ups of not only stills, but also home videos on the big screen.

DICOM SIM is a very rare mode. This is a Canon trademark. Frankly speaking, I’ve never come across it. All I can say is that this is a simulation of the DICOM standard Digital Imaging and Communications in Medicine , an industry standard for creating, storing, transmitting and visualizing medical images and documents.

Luminance is globally interspersed

After the projector has warmed up for about 30 minutes, we measured the illumination of various parts of the image with a Testo 540 Luxmeter. This was done by displaying a plain white image of 255R, 255G, 255B. Measurements were taken in places marked with red dots.

The brightest point of the image, the center, was taken as 100% and the value of the others was determined as a percentage of it. In order to color the image squares, the color was chosen as follows: 255R, 255G, 255B * percent relative to the brightest point, rounded according to the rules of mathematics. For example the value of 81.4 percent corresponds to the color 208R, 208G, 208B in RGB space or simply 208 in GrayScale space.

The test result is excellent! The brightness drop in the image corners is 10 percent. To the eye these differences are practically invisible. Even in the white picture where the vignette is most clearly visible. Moreover, even serious monitors cannot boast of such indicators. By comparison, the previously tested cinema projector of another Japanese brand had twice the brightness degradation in the corners.

Color gamut – don’t want to cover more?

Let’s pass to consideration of CIE diagrams, which will allow us to estimate the color coverage, color temperature and the presence of the parasitic shades.

The color gamut of our test subject is a little bit displaced relative to the sRGB standard. In reds and blues, the coverage exceeds the limits of the standard triangle, and in greens, it’s clearly underdone. Good or bad? If we spoke about the cinema projector of Hi End level one could shrug his shoulders when looking at such triangles. But multimedia sets have different requirements. If the projector is going to be used as a primary specialty in a conference room, most likely no one will notice the shift in color gamut. And yet..

Red goes beyond the standard. That’s probably why I saw reddish tints on the yellow-orange objects in the visual test of this projector.

Blue also crawls out of bounds. But this color in its pure form is rare enough to see on images. In view of the peculiarities of human perception, a too blue color is not perceived as negatively as a too red one. So, because of “extra” blue and red colors there should not be serious problems with the image.

This is not the case with green tones. Look at how much of these tones are missing from the projector. How it will turn out on the screen? In short, the succulent grass of May is likely to become the grass of July from the top of summer. But as we’ve found out, the main job of a multimedia projector is not to lie on the grass…

However, in the next release of the projector, the color triangle is likely to be as close to the RGB standard as possible. The thing is that the image in the device is formed by three monochrome LCoS-panels RGB . If two matrixes can “overflow” blue and red, then the third one will also be able to add green shades and the other two will on the contrary diminish the excess. Factory technologists may consider our wish to be a personal order.

Note also that the color gamut settings are very similar in different modes. Slight differences can be seen because the modes have different gamma curves and other settings. By the way the DICOM SIM standard provides the best display of green shades.

A gray wedge is flying, flying through space..

Let’s go back once again to the color gamut diagrams. Now look and try to understand all about the points of the gray wedge, which will identify parasitic shades and quite accurately put the image color temperature.

Standard mode – most of the gray wedge points fall into the second confidence interval, corresponding to dE=10. The bad thing is that the dots are not grouped in a “bunch” but lined up. And this line does not coincide with the color temperature curve. This means two things. First, the color temperature will change depending on the lightness of the image. How exactly we’ll see in the following charts. Secondly, it means the presence of parasitic tints, although not very significant, because most of the points fall within the confidence interval. Since some points are below the curve and some are above it will mean that the parasitic colors will be complex, both cool and warm.

Presentation mode – the color temperature situation in this mode is described as catastrophic. The gray dots are too far apart. This means that the color temperature is very unstable. It varies from about 5000K to 7500K. This is not good for the color reproduction we’re talking about. For example, if we have a rock that goes smoothly from the light part where the sun falls to the dark part that is in the shade, then one part of it will be warm and the other much colder. It will be very noticeable. Presentation mode, on the other hand, has never been about color accuracy.

Photo/sRGB mode – the mode does not live up to the second part of its name. It doesn’t even roughly cover the sRGB color space. The points of the gray wedge are concentrated on the warm border of the confidence interval. Consequently, the color temperature is stable and warmer than 6500K. All in all, it’s not too bad. A slightly warmer picture is always more pleasing than a cooler one. The dots do not deviate significantly from the color temperature curve, and therefore there will be no serious stray shading.

DICOM SIM mode – of all the modes, it’s in this mode, the gray wedge points are closest to the required 6500K. They are all located on the color temperature curve with a slight shift to the blue-magenta area.

So the color gamut of the projector corresponds to an average monitor. No major differences in color gamut between modes. But the color temperature of each mode definitely has its own, but more about that in the next section of testing. As for the compliance of the names of the modes with their practical application, it’s too early to speak about that, except for the fact that in Photo/sRGB mode the declared color space is not fully displayed by the projector. But the photos in this mode will have pleasant warm shades.

What is your color temperature?? Color.

Let’s take a closer look at the color temperatures of each mode. The presented charts allow you to estimate the color temperature when you change the lightness, but unlike the previous charts, they do not give you an idea of the presence of shades.

In Standard and Presentation, the color temperature increases with the lightness level. And vice versa: Decreasing color temperature with decreasing lightness. In other words, the shadows will have cool colors and the lights will be warm. In the case of presentation mode, very warm.

In Standard mode the ideal color temperature is reached at 60. In Presentation mode, it is at 40 percent. By and large we get a free common element of portrait photo processing – split-tone, which gives the shadows a cool tint, and in the light parts of the picture – a warm one. However, when this effect is always present, it is also too much.

For Standard mode the average color temperature is about 6400K. It is impossible to get a final color temperature for the Presentation mode. But it’s definitely warmer than the 6,500K.

In Photo/sRGB mode, the color temperature is almost stable. The exception is the jump of 40 percent lightness. Except for this jump, the color temperature ranges from 5500K to 6000K. Images will be slightly warm, but not yellowish. In terms of color temperature, we can safely recommend this mode for viewing photographs.

The DICOM SIM mode is very pleasing. The color temperature is almost stable and very close to the reference 6500K.

This mode is the leader in my internal rating. Judge for yourself – the most adequate color gamut, especially in the area of green tones and the most accurate color temperature is a serious bid for the “yellow jersey” leader.

Gamma curves: four lines, like lines of fate

Let’s look at the channel-by-channel gamma curves. They show how accurately the details in the shadows and highlights will be reproduced, as well as the overall contrast of the image. You can also talk about color distortion based on gamma.

In Standard mode, the red and green channel curves are very close to the reference. This means that shadows and lights will be transmitted most accurately. Provided these shadows or colors are not blue or derived from that color.

The blue channel gamma curve rises quite a bit above the reference. If there is a lot of blue in the picture, it will look a bit lighter than it should. Also, a strong stratification of gamma curves of channels can lead to color distortions, which are clearly visible on RGB level diagrams.

Gamma curves of the Presentation mode have a very strange, but already familiar to us from previous reviews S-shape. Moreover, the blue channel again rises much more above the reference than all the others. Blue is the opposite of yellow. Notice how the closer you get to 100% brightness, the less blue gets, and therefore the more yellow gets. Here we have the answer why the color temperature of this mode begins to grow so much with increasing brightness.

Nevertheless these gamma curves perfectly fulfill their function of increasing contrast readability of midtones, by sacrificing details in the light area. And that’s exactly what you need for Presentation mode – to make text or graphics readable in bright light. There is no point in talking about the accuracy of light and color rendering when you only need to see letters and numbers.

The gamma curves of the Photo/sRGB mode are very close to the reference. I expected this. If the manufacturer states that the mode is intended for photography, accurate light and color reproduction is quite logical. It is very good that the gamma curves of the channels practically do not diverge from each other. Sometimes this is even more important for picture accuracy than the correct shape and position of the curves.

But the DICOM SIM mode, unlike the others, has a lower gamma. And the understatement is typical for the bright parts of the image. So visually the projection will look a little darker and less contrasty in the middle and dark areas. But the details in the highlights should be clearly visible. By the way, such image settings are very convenient not only for reading tests, but also for viewing purely medical images: X-rays and tomographs.

In general, the gamma curves of each mode correspond to its name.

And will this Gamma Gummi Bears like it??

Now let’s see how the channel gamma curves merge. The graphs show the gamma value depending on the level of lightness of the image. Recall that the reference value of 2.2.

The graph of the Standard mode is very similar to its color temperature graph. In the lighter parts below the reference, in the darker parts, on the contrary, higher. It would be better to do the opposite. Under the current situation, it turns out that the shadows will be darker than necessary, and the light areas will be lighter. This could lead to details not being seen there or thereabouts. The visual test showed that the shadows are still distinguishable, but there are really problems with the light areas. You can’t always make out all the details.

As you might expect, in the Presentation mode, the graph is very far from the reference. The main thing here is not the accuracy of colors and light rendition, and readability of graphs and tables, that is – the average tone, even in bright light.

Looking at the graph of the Photo/sRGB mode, we can say that the image in the shadows and the dark part of the middle tones will be a little darker than it should be. The midtones are almost ideal, but the lights are too light at 70% of brightness and too dark at 100%. There is nothing wrong with decreasing gamma in the light area for the projector.

This can save them from “failing” in bright light. Of all the modes, it is probably the Photo/sRGB mode that is the most adequate and recommended in terms of gamma. So you can watch cartoons about Gummi Bears with great pleasure. The Gummi Bears will love the way they are shown

DICOM SIM mode has an inflated gamma. Nevertheless, the shadows have a normal gamma, which makes it easy to distinguish details in them. But closer to the light area, the gamma becomes more and more. Visually, it looks something like this: the image becomes less bright overall, lights are slightly muted, and there is more detail in the lighter areas of the image.

The contrast the difference between the lightest and darkest points remains the same, but due to this gamma the image becomes more flat and quiet, but the details, especially the light and midtones are very, very well distinguishable. The image is peculiar, but I personally like it. They say that foreign doctors also really liked the Canon projector’s own medical image mode.

RGB levels have become the “holy trinity” in color reproduction

RGB levels are one of the main tools for color calibration. Ideally, the values of the channels should be identical and at 100 percent. In this case, the grayscale will be neutral and the color calibration is top notch. By the deviations of the graphs from 100 percent we can judge the presence of a particular shade in the grayscale.

If it were not for the blue channel values in Standard mode, the RGB levels would be very close to ideal. The current situation illustrates that reducing the level of blue to the light leads to a warming of the image, which we talked about in the color temperature section. dE, illustrated by the pink line, is not very high. Up to a luminance level of 70 percent, it does not exceed 5. And it is only in the Lights that it reaches its maximum of 10.

In Presentation mode, in terms of RGB levels, everything is similar to the previous mode. However, this is compounded by the fact that the green and red channel levels differ from each other by about 15 percent. Not the best gamma, which leads to low quality color rendition and presence of stray color shades. Primarily the yellow-orange ones. Up to 50 percent brightness, the dE does not exceed 7.3. This is not a bad result.

But closer to the light zone the deviation reaches very high values, the apogee of which is the value of dE=36. As we have already mentioned, these objective measurements only show that the Presentation mode is set up exclusively for presentation, where it is necessary to keep the other parameters at a high level: brightness and contrast.

In Photo/sRGB mode, the difference between channel levels is minimal. Only red is slightly more than the others, which gives a higher color temperature. By the way, this profile is quite good overall. This is confirmed by the fact that the dE even in the bright areas does not exceed 8.

In terms of RGB levels the DICOM SIM mode is the best. The channel levels are closest to each other and to the ideal value of 100 percent. In terms of RGB levels, this is the best mode. The dE up to 90 percent is less than 5. And only the 100 percent brightness level is associated with an increase in deviation.

The final table is like a podium

Let’s look at the contrast values. In all modes this parameter doesn’t cause any troubles, being higher than 1000:1. The highest contrast value, as one would expect, is in Presentation mode – 1697:1. The other two modes have a similar contrast of about 1175:1. It’s a very, very good indicator. No contrast problems with the image.

Average gamma value for all modes was quite expected and was close to the reference 2.21 in Standard mode and 2.28 in Photo/sRGB mode. Overestimated to the level of 1.63 gamma for Presentation mode. And an underexposed gamma 2.55 in DICOM SIM mode. It seems that in the Standard mode gamma is almost ideal. But please remember that this is the “average hospital temperature”.

The average grayscale deviation is similar in all modes except for the Presentation mode and is a little over four. Presentation mode has a very high deviation of dE=13.78. The main color cast in this case is yellow-orange. It will not be an increase in color temperature, but rather a parasitic tint.

I will leave the deviations of primary and secondary colors for the reader to study, as always.

The average deviation in primary and secondary colors is minimal in Photo/sRGB mode. This confirms once again that the mode lives up to its name.

Standard and DICOM SIM modes share the second place on this parameter. Their deviations are 23-25. The result is quite acceptable for a projector. This result is comparable with the TN-matrix of a mid-range notebook. The only difference is that laptops usually cool the image, while our test subject, on the contrary, in most modes “mows” to the warm zone. I’ve already mentioned about Presentation mode more than once – I’ve set it up for what I want and what I’ve got it for.

To make it clear I will give you a couple of color examples to illustrate mode deviations:

dE=15.8

dE=22.0

dE=33.0

Wishes in a cube: how to improve an image?

Our graph, which hopefully will become a signature feature, graphically depicts the characteristics of each mode. As axes this time we chose: color temperature, gamma value, and gamma shape.

Let’s pass to the promising characteristic of each mode, recommendations for its use.

Standard mode we already gave the detailed description of this mode in the visual test of the projector. Decent contrast, standard color gamut for that monitor. The low stability of the color temperature makes the shadows look a little bit cool, and the lights on the contrary, a little bit warm.

In this mode, the image gravitates towards different shades, both cool and warm. Although the shadows are darker than they should be, they are still distinguishable, but there can be problems with the light areas. Sometimes it’s impossible to distinguish details in them. The color deviations are averaged with respect to our test subject.

Presentation mode – we don’t speak about the cinema quality of the image. The picture is intentionally changed to suit the main goal, which is to make text, tables and charts readable even in very bright direct light in a large room. And the mode actively copes with this function, because it has the highest contrast and brightness of all the others.

The Photo/sRGB mode is a very interesting mode. Its main disadvantage is the high color temperature. Gamma and gamma curves are very close to the reference, minimal dE values for grayscale, primary and secondary colors, decent contrast.

In this mode, the shadows are still easily distinguishable, with a significant increase in contrast in the bright area. And therefore the details in the light area will be much easier to distinguish. And, best of all, there is a solution to get rid of this mode’s only flaw – the warm color temperature. That it can be used not only for viewing photos, for which it is perfectly suited, but also as a basic mode for all occasions, including watching video.

DICOM SIM mode – frankly, this is the first time I’ve encountered such a standard intended for medical professionals. I will only describe the measurement results and general impression of the picture. The mode has, although not the highest contrast, it is still high enough to provide excellent black and white images. It has a pretty low grayscale variation and average deviation of primary and secondary colors.

Color rendering in general is very similar to the Standard mode. Shadows are well defined. Lights are very dark and contrasty at the same time due to the low gamma value. The image appears darker for this reason, which guarantees very sharp images in X-rays and CT scans. As it turned out, thanks to the Canon projectors the transition process from conventional X-ray films to digital format has started in foreign medical centers.

What it adds up to? I would recommend using each mode by its name.

BUT! Photo/sRGB mode is definitely better in all areas than standard mode, except for color temperature. That’s why I would recommend adjusting the Photo/sRGB profile and saving it as a custom profile for everyday use.

For that it is necessary to turn down the color temperature by reducing the red channel level in the projector settings. And then all the RGB levels merge, providing an accurate color temperature. How much lower? There is no clear answer. The guideline here is that if an adjusted image starts to smell cold, it means that you overdid it and need to correct it again… As a result, you can get a profile with excellent light and color rendering.

Conclusions

As a result of independent testing, we are convinced that the Sapp WX450 ST projector can work in at least three professions.

The projector has such a bright and contrast image, which, coupled with a short focus will be indispensable for seminars and conferences in public halls. Beautiful presentations, instantly adjusted slideshows and videos are appreciated by the widest audience.

The new profession for the projector is the assistant to the attending physician, especially the surgeon and trauma surgeon who work with x-rays every day. Now it is possible to refuse from usual films and switch to digital images for conducting medical counseling.

A Canon projector can also easily become the heart of an above-average home theater. It does not pretend to the Hi-End level from the beginning. But after adjusting user mode is able to show very interesting movies!