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Acer K335 LED Projector - Image Quality

Posted on February 3, 2014 by Art Feierman

Acer K335 Projector - Readability

For the initial tests the input from the laptop PC was set to the Acer K335's native resolution (i.e., 1280 x 800).  This is expected to result in the best case sharpness for displaying text for business presentations since the projector does not need to apply any video processing to scale the image to the projector's display resolution.  With this type of input the K335 provided a nicely sharp image and even the very small 8-point type being fully legible.

The K335 offers an assortment of projection modes and I felt for business presentations the "Standard" mode offered a reasonable trade-off between the somewhat conflicting goals of desiring the maximum light output and also desiring accurate colors.  Unfortunately, in "Bright" mode (which was by far the brightest mode), colors were significantly worse than they were in "Standard" mode.

The photos taken from the screen show the K335's relative good performance for displaying text.  The first photo is a full screen image while the second, third and forth photos below are close-ups showing the projector's ability to display the smaller text fonts.  I would note there was some color fringing visible when viewed up close and this is due to modest amount of chromatic aberration being introduced by the projector's lens.  This amounted to a maximum of about a half pixed offset between the green and red color components.

Text - Test Image

Photo of Text Image with 1280 x 800 Resolution Input

3-Text Pic-2

Close-up Photo of Text

3-Text Pic-3

Close-up Photo of Text

3-Text Pic-4

Close-up Photo of Text

 

The above screen shot photos were taken when using our usual spreadsheet, which has a range of text sizes and colors, the K335 provided a sharp, clean image at its native resolution (1280 X 800).  All text color and size combinations (from 8 pt. to 36 pt. text and white text-on-black or yellow text-on-dark blue backgrounds) were very readable, with only modest individual color fringing visible when viewing near the screen.  This was with a projected image size of just over 80 inches wide, which is a little larger than the maximum size I would recommend for the K335.

The next two photos show the same text test screen, but with the resolution from the PC to the projector set to 1920 x 1080.  This means the Acer K335 must scale the image down to the native resolution of its display.  This is a test for the scaling capabilities of the projector.  The K335 did very well in this test as the displayed text is not noticeably degraded by the scaling.

3-Text 1080p Pic-1

Photo of Text Image with 1920 x 1080 Resolution Input

3-Text 1080p Pic-2

Close-up Photo of Text with 1920 x 1080 Resolution Input

 

Switching to higher resolutions and aspect ratios, the K335 performed quite well.  For example, at a 1920 x 1080 (a higher resolution and different aspect ratio) resolution, the K335 displayed some red/green fringing (the cause of this is achromatic aberration caused by the lens and not a result of the scaling).  However, taking the time to get a near perfect focus helps achieve the most readable text, and even the small (8 pt.) text remained quite readable.  Moving down in resolution below the K335's native 1280 x 800 resolution resulted in the projector only displaying an image with the resolution of the input.  For example, when a 800 x 600 test signal was input the projector displayed the image only in the central portion of the 1280 x 800 image frame.  By that I mean the projector did not upscale the input to match the projector's native resolution.  Overall the Acer K335's scaling capabilities produced excellent results.

 

Acer K335 Projector - Video Quality

The Acer K335 color accuracy was evaluated in each of the factory picture modes.  When standard color test patterns were projected with the K335 operating in "Bright" mode, the image had a  strong green appearance (e.g., whites appeared too green) and greens in the projected images appeared too bright while the blues in the image appeared too dim.  Although the red and blue color saturation levels may have been reasonably accurate, green was substantially over saturated, yellow appeared somewhat green, cyan appeared too blue and magenta had an excessive blue hue.  Overall the colors were rather poor with the K335 operating in "Bright" mode.

"Standard" mode produced a significant lower light output than the projector's "Bright" mode, but the projected images had more accurate colors and overall were more satisfying for viewing.  The green was still over-saturated and, yellow appeared too green while the remaining colors were closer to the correct saturation and hue points than they were in the "Bright" mode.    The pronounced overall green appearance present in 'Bright" mode was replaced with a less pronounced, but visible, overall red appearance in "Standard" mode.  Reds in the projected images appear a little too bright.  Overall the projected images, with the projector operating in "Standard" mode, would be considered more than  acceptable for most business presentations.

By default both the "Bright" and the "Standard" modes, as well as 'Game' and 'Sports' modes, have "Brilliant Color" turned on.  While the "Movie" and "Dark Cinema" modes do not permit the use of "Brilliant Color".

When the Acer K335 is to be used for projection of video or photographs, where the quality of the resulting projected image is frequently more important than need the brightest image, then the K335 offers a "Movie" mode and a "Dark Cinema" mode.  Both of these modes still had an over-saturated green, but the other colors had reasonably accurate saturation and hue.  However, in both of these modes, and using the factory default values for the other settings, the overall color temperature of the projected images was very low (i.e., near 5,000K instead of the standard 6,500K for video).  This was due to a large degree by a much too high intensity for the red color and as a result the reds in the projected images appeared too bright as compared to the other colors. In these modes skin tones appeared too red and although this was less objectionable than the too green appearance in the "Bright" mode,  it was nevertheless less than ideal.

The projector offers a color temperature adjustment with 3 preset values labeled CT1, CT2 and CT3.  All of the above observations were with the color temperature adjustment set to its default CT2 value.  I found that when using the "Movie" or "Dark Cinema" modes changing the color temperature setting to CT1 produced somewhat more accurate color, but there was still some excessive red intensity.

The "Game" and "Sports" picture modes appear less accurate than the "Movie" and "Dark Cinema" modes but certainly more accurate than the "Bright" mode.

Below are a series of photos showing how the colors vary with the projector's different picture modes.  The first image below is the electronic test image itself and can be used as the reference for what the colors should look like.  I must note that it is difficult to capture in a photo taken from the projection screen exactly what the human viewer will see and the exposure of the photos below makes them appear a little darker than the reference image below.

Reference Color Test Image

Reference Color Test Image

Bright Picture Mode

'Bright' Picture Mode

Standard Picture Mode

'Standard' Picture Mode

'Sports' Picture Mode

'Sports' Picture Mode

 

'Game' Picture Mode

'Game' Picture Mode

 

'Movie' Picture Mode

'Movie' Picture Mode

'Dark Cinema' Picture Mode

'Dark Cinema' Picture Mode

 

I also noted that when the input signal is in RGB format, such as typical from a PC, the projector's adjustments for color "saturation" and "tint" are not available, although equivalent color adjustments should be available on the PC itself.  However, when the input signal is in component video format (i.e., YCbCr) the projector's menu offers traditional color 'saturation' and 'tint' adjustments.

When the user elects to adjust any of the picture setting, such as brightness, contrast, color temperature, etc., the K335 switches from the current preset mode into "User" mode where one set of user settings can be stored.

Given the limitations of the K335's preset modes the real question becomes it is possible to find a combination of user settings that will produce a reasonably accurate image for displaying video or viewing photos.  Note this projector has no user accessible adjustments that allow for calibration of grey scale or color gamut, nor does Projector Reviews normally attempt to calibrate business or education class projectors for our reviews (even those projector that offer such advanced controls).  Using the available user adjustments I found that for watching video from a Blu-ray Disc player I preferred to use "Movie"  mode as a starting point then I set the color temperate  to CT1 and the color "saturation" adjustment a few clicks below it default value.  However, even with these settings the skin tones appeared somewhat excessively red and objects with a bright green color (e.g., grass and trees) appeared to almost glow in some scenes  Yellows appeared to have a green tint and red objects appeared too bright.  Dark scenes appeared rather flat due to the relatively low contrast of the K335 and shadow details faded into a grey background.    I simply could find no combination of settings that produced truly accurate colors.  While it would probably be considered watchable to the casual viewer and certainly adequate for showing an occasional video as part of a business presentation, but the K335 is  far from ideal for use as a full time projector for TV or movie viewing, but of course that's not the market segment the Acer K335 is attempting to compete in .

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