- Written by Ofer Laor
- Published on 03 October 2012
The Darbee Darblet DVP5000 Video Processor In Use
What was tested:
- Analyze and the effects of the Darblet, see if there are any artifacts or issues with the produced image.
- Verify that the unit does not deteriorate or reduce image quality somehow.
- Check if I personally like the effect or not.
The first two tests are completely objective, while the latter is completely subjective. Many videophiles and HT enthusiasts really like the Darblet, and I indeed wanted to see what all the fuss was about.
The unit has 3 modes: HD (green), Gaming (yellow) and full pop (red). As I'm not really a gamer, I analyzed all 3 with video material only. Interestingly, the three modes are essentially variations on two different algorithms that seem to be weighed in differently depending on the mode. The filters seem to have some parameter variations depending on the mode – HDTV focuses on contrast enhancement with a lighter dose of sharpness, while full pop focuses primarily on heavily sharpening the image. The yellow gaming mode seems to be a mix of the two, which meant it was much more of a compromise than being truly functional.
Contrast stretching is a well known feature that you can find in many cameras, Photoshop or even freeware like Picasa (auto contrast). It was actually implemented in video processors like the Lumagen XD/XE series. In this case, a much more localized contrast stretching algorithm is used, which produces a much more subtle result. The effect is like lifting a layer of film right off the image.
Sharpness is also a very popular filter found on every display and projector. Usually, the first thing a good calibrator does is turn sharpness off to remove any of the annoying halo edge enhancement artifacts that these algorithms produce.
You can see an exaggerated contrast enhancement algorithm at work here:
My first test was to try and figure out if the unit was harming any of the video. The Darblet converts content to 4:4:4 internally and then back into your original content source format (RGB or 4:2:2), so I recommend to keep your source at 4:4:4 when possible to avoid unnecessary format conversions. Other than that, the unit performed without interfering with the content – no lipsync issues, no gamma changes or color gamut changes. The unit slightly increases the HDMI sync times, but it is overall transparent and does not cause any issues with the video.
The unit worked in all framerates, resolutions and even 3D.
I started with SD and saw that the results were pretty bad. The unit brought out many of the compression artifacts unless turned quite low. I recommend against using this unit with SD content.
Next, I turned the unit to full pop mode to see what it would do with a 720P signal.
The following images were created by slowly increasing the processing strength from 0% (off) to 120% (spinal tap anyone?).
You can see that as the processing gets stronger, the facial features become more pronounced and harsher. The contrast also becomes stronger and more stretched (but localized).
Using a test pattern, you can see artifacts past 40% at full-mode. The artifacts appear as left and right smears on the horizontal plane. They are most pronounced on the left and right horizontal lines.
The HD mode does not exhibit this behavior and is far less prone to artifacts even when set to the highest setting.
Using a high frequency pattern, you can see that the center circle slightly changes its shape to more of a rhombus shape.
Adding contrast without artifacts
Darbee's challenge is to add more contrast and sharpness to the image without introducing artifacts.
The next few images demonstrate how Darbee attempts to do this:
The Original Image.
The difference map between the two:
As you can see, Darbee focuses on changes on a few fronts. First, it enhances the cheek and hair on the right side of the image. This is done by brightening the light part of the face. Usually, this is contrasted by a darkening of the outer edge of the face, thus producing an artifact called "ringing" or "overshooting", but Darbee avoids this.
There are also some enhancements to the lips and nose and a slight enhancements to the freckles. Nothing to outstanding, but enough to make these more pronounced.
Lets take another image and analyze it:
This is the original image. Lets enhance it using a VXP adaptive contrast algorithm (using a Lumagen XE).
As you can see, this algorithm brings out many details but does not sharpen the image at all.
You can see there are details enhanced across the entire range of the image and the face.
This is the image at full pop 45% (my recommendation for this mode):
The difference map is interesting - it focuses on the left side of the face, the ear and the right side, but does not bring much enhancement to the details of the face itself.
At full pop 100%, the difference is more dramatic:
Here, you can see that the edges of the face are much more pronounced (notice the brown edges of the forehead), but there are many facial details enhanced as well.
At HDTV 45%, you get a much more balanced enhancement, which brings out the edges a lot less, but does increase the contrast much more (note the facial features are more pronounced).