Archos Diamond Omega: Solid performer

Launched in November 2017, the Archos Diamond Omega offers some impressive photo and video specs, as befits the firm’s flagship model, starting with a dual rear camera and 4K video capture. The rear cameras are a high-resolution 12MP f/1.8 primary camera and a 23MP f/2 for enhanced zoom. The dual camera setup also allows for a Portrait (Bokeh) effect. Neither camera module features OIS, though. The camera modules appear to be essentially the same as the ones in the Nubia Z17S (and image EXIF data also reports that model). The Omega also offers 4K video at 30fps (or 1080p at 60fps).

Like many other flagship phones, the Omega packs a Qualcomm 835 chipset, which gives it enough power for sophisticated image processing, for example, its built-in HDR mode and electronic image stabilization. Its 5.73-inch 1080 x 2040 pixel IPS display is protected with Gorilla Glass. The phone also supports Quick Charge 3.0 for rapid recharging, and it has a fingerprint sensor on the rear.

Key camera specifications:

• 12MP primary camera with f/1.8 lens (1.4 micron pixels) (reported as 25mm equivalent focal length)
• 23MP secondary camera with f/2 lens (reported as 22mm equivalent focal length)
• Phase-detection autofocus
• Dual-LED, dual-tone flash
• 4K 2160p video at 30 fps
• Face detection, HDR, panorama mode

About DxOMark Mobile tests: For scoring and analysis in our smartphone camera reviews, DxOMark engineers capture and evaluate over 1500 test images and more than 2 hours of video both in controlled lab environments and in natural indoor and outdoor scenes, using the camera’s default settings. This article is designed to highlight the most important results of our testing. For more information about the DxOMark Mobile test protocol, click here. More details on how we score smartphone cameras are available here.

Test summary

The Archos Diamond Omega features a reasonably good camera, but doesn’t excel in any specific area other than in having quick autofocus and generally accurate exposures. Its 80 point overall score is in line with the upper-end phones from mid-tier players, but behind the top-tier flagship devices from Apple, Google, and Samsung. While casual photographers will find that it captures scenes well under good light, photo enthusiasts will be bothered by its lack of detail in high dynamic-range scenes, as well as by image artifacts that become very visible when looking at the image on a large screen or when printed.

Its unusual combination of a primary 12MP camera and high-resolution camera mean that it zooms by cropping the higher-resolution image. Unfortunately, that camera has smaller pixels and therefore more noise than on a phone with a true telephoto camera. The lack of optical image stabilization, and of any kind of stabilization in the default mode for capturing video, also holds the camera back.

Bright light

In outdoors and bright light, the Omega produces excellent exposures and focuses quickly and accurately. Its color reproduction suffers, though, with color shading and some white balance errors. Detail is well-preserved, but noise can be an issue in highlight and shadow areas, even in outdoor scenes.

The Omega does a very good job preserving details in outdoor scenes, and renders them in an overall pleasing way. If you look closely, you can see noise in the sky, but it is most pronounced towards the edges of the image, so it isn’t very visible to a casual observer.

While noise was an issue in solid areas such as the shadowed portions of buildings or blue skies, it was well-contained in textured areas, such as the patterned portions of this building, in all tested conditions.

The Omega does a generally good job of detail preservation when used outdoors.

Low light and Flash

The Omega does a remarkably good job of accurately focusing and correctly exposing under low-light conditions. However, as light falls, detail preservation begins to suffer greatly, despite aggressive noise reduction. Color continues to be an issue, with shading and white balance errors.

This typical indoor scene is well-exposed, but suffers from a slight color cast. A close look at the full-resolution original also shows some noise in such large solid-colored areas as the note board.

Using flash, the Omega continues to expose well, but images suffer from a green cast. There is also noise and some visible color quantization in important areas of the scene, such as the subject’s skin.

Zoom and Bokeh

The second, high-resolution camera on the Omega helps it score well in the zoom category, although not as high as some of the leading dual-camera models. Unfortunately, the second camera isn’t very effective at providing good depth or bokeh effects.

While the depth (bokeh) effect works well for some parts of this 1000 Lux test image, you can see significant errors — for example, at the top of the image in the downward-pointing triangular shapes.

Photo scores explained

The Archos Diamond Omega achieves a total photo score of 82, which is calculated from its scores in tests that examine different aspects of its performance under different lighting conditions. In this section we’ll take a closer look at these image quality sub-scores.

Exposure and Contrast

Archos Diamond Omega

85

The Omega does a good job of calculating target exposure for naturally-lit scenes, even in low light. Exposures are quite consistent from outdoor down to typical indoor lighting levels and fall off only slightly even in very low-light conditions. The Omega even does an excellent job of calculating the optimal exposure in fairly tricky scenes, such as this backlit indoor portrait with light streaming through a window:

The Omega handles exposure very well in this backlit portrait shot. It correctly exposes the subject’s face, while many other cameras would render the scene too dark. However, its limited dynamic range means that the outdoor highlights are blown out.

Even in extreme low-light conditions, the Omega exposes accurately, as illustrated by this test scene shot with just 1 Lux of ambient light.

The Omega image of our studio test chart shot at a light level of 1 Lux shows accurate exposure, although you can also see color shading and substantial loss of detail.

Despite having built-in HDR capability, the Omega does not do a particularly good job of holding details in the bright portions of high-dynamic-range scenes. In this image looking out from under a bridge, you can see that it doesn’t preserve the details in the sunlit portion of the river. It also is unable to hold the details in the very dark area on the underside of the bridge. You can compare its performance to the iPhone 7 Plus and the Nokia 8 photographing the same scene, and see that the iPhone 7 Plus does a better job of preserving details in the bright portions of the scene — especially the water. Click on a thumbnail to see the entire original image from each phone:

Archos Omega

iPhone 7 Plus

Nokia 8

Color

Archos Diamond Omega

71

Color rendering is not one of the Omega’s strong suits. There is strong color shading (inconsistency of color across the image) in all lighting conditions, and colors also tend to be desaturated.

Colors are often desaturated, as illustrated in this image.

A pink cast appears in the center of images under a variety of lighting conditions, including in this image of a studio test scene photographed at 20 Lux, hand held.

Taking a closer look at the rendering of individual colors, in many cases the Omega has a hard time rendering them accurately. Here, for example, are the test results for the skin tone patches of a test chart photographed under a variety of lighting conditions and compared with the reference patch color in sRGB:

The Omega has trouble with the lighter skin tone patch in all lighting conditions, and also struggles a bit with the darker patch.

White balance is also inconsistent, even under good lighting conditions:

The Omega has a color cast for neutral patches in most lighting conditions.

Autofocus

Archos Diamond Omega

94

The Omega excels at autofocus, taking advantage of its dual-pixel sensor and laser assistance for quick focusing under all lighting conditions.

Even in low light, the Omega does an impressive job of providing quick and repeatable autofocus, as you can see here from our test results at 20 Lux. The Short Delay and Long Delay times are the intervals we provide the camera for refocusing, and the dots represent how soon after that it captures an image. If the autofocus fails, the dots will appear lower on the chart. As you can see, the Omega focused correctly every time.

Texture / Detail (54)

The Omega does an okay job of preserving detail in great conditions, but once the light starts to fall off, texture preservation suffers greatly. You can see this illustrated with these crops of three handheld shots taken with the Omega, the iPhone 7 Plus, and the Sony XZ Premium under decreasing light levels, at 1000 Lux, 100 Lux, and 20 Lux (a fairly typical light level for indoor events).

At 1000 Lux, you can already see that the Omega shows a little less detail than the other models, although due to more aggressive noise reduction, it produces a smoother background:

Crop from Omega at 1000 Lux.

iPhone 7 Plus at 1000 Lux.

Sony XZ Premium at 1000 Lux.

At 100 Lux, the Omega manages to retain nearly the same image quality as it did in brighter light, while the other two phones start to lose a little detail:

Crop from Omega at 100 Lux.

iPhone 7 Plus at 100 Lux.

Sony XZ Premium at 100 Lux.

At the lower light level of 20 Lux, the loss of detail in the Omega image is quite pronounced, especially compared to the Sony:

Crop from Omega at 20 Lux.

iPhone 7 Plus at 20 Lux.

Sony XZ Premium at 20 Lux.

You can see the different trade-offs made by Archos, Apple, and Sony here, as the iPhone and XZ Premium preserve more detail in low light, while the Omega applies additional noise reduction at the expense of detail preservation.

Noise

Archos Diamond Omega

67

The Omega has a lot of noise in blue skies and shadowed areas, even in well-lit outdoor scenes. It is particularly noticeable when the scene is high-dynamic-range, like this one facing the Eiffel Tower:

There is visible noise in the sky, even in a reduced-resolution preview of this brightly-lit outdoor scene. If you click through to the full-resolution version, you can also see substantial noise in the shadow areas under the bridge.

You can compare noise levels among the Omega and the similarly-positioned Apple iPhone 7 Plus and the Sony Xperia XZ Premium using these cropped sections of our studio test scene. The Omega works hard to remove noise, but some details are lost as a result, and textures look less natural:

Crop from Omega at 20 Lux.

Crop from iPhone 7 Plus at 20 Lux.

Crop from Sony XZ Premium at 20 Lux.

Artifacts

Archos Diamond Omega

48

The Omega is particularly susceptible to artifacts that are quite visible when looking closely at an image. Ringing and aliasing are quite common:

You can see obvious ringing around many of the edges in this image.

In lower-light conditions, there is also a problem with ghosting if there is movement in the scene. In the case of the backlit portrait below, you can see it both in the moving hand and in the static top edge of the window. Loss of sharpness is also an issue for the Omega, especially when you look closely. The outdoor scene below on the right is sharpest in the middle, with less detail towards the edges In mixed light (flash plus ambient), the Omega also develops slight exposure instability, with sequential frames appearing either lighter or darker than previous ones.

You can see the ghosting of the subject’s moving hand in this low-light scene, as well as in the top edge of the window.

You can see that detail preservation falls off as you go towards the edges of the frame in this outdoor image from the Omega. The railings are sharpest in the center, but lack detail on the sides and the top and bottom of the image.

Flash

Archos Diamond Omega

75

As with other lighting conditions, the Omega does a good job with exposure for flash-lit scenes. However, scenes lit only by the camera’s flash have a visible green cast to them. If you look through to the full-resolution image, you can also see some low-frequency noise and color quantization in faces. With mixed lighting, the white balance is too green, and color shading becomes visible.

Exposure is excellent in this scene lit with the Omega’s flash combined with 5 Lux of ambient light, but the image has a green cast. There is also poor detail preservation in the subject’s face, and a slight red-eye effect is noticeable.

Zoom

Archos Diamond Omega

30

Rather than have a second camera with a longer focal length, the Omega has one with a fairly standard focal length, but higher resolution, so that zooming is accomplished by cropping its 23MP image. The resulting system works well in many cases, but has some definite issues. Detail preservation can vary from frame to frame, for example, and noise is an issue in large, solid-color areas.

Texture is reasonably-well preserved in this frame of an image taken using zoom.

However, in other frames taken of the same scene, there is noticeable loss of detail.

Omega medium zoom.

iPhone 7 Plus medium zoom.

Nokia 8 medium zoom.

In our long-range Zoom tests, the Omega loses additional detail, especially compared to the iPhone 7 Plus, but it holds up much better than the Nokia 8, where not only is there a dramatic loss of detail, there is also a large increase in noise:

Omega long-range zoom.

iPhone 7 Plus long-range zoom.

Nokia 8 long-range zoom.

Quick note on our Zoom tests: The medium-range tests correspond to a 4x–5x magnification depending on the native focal length of the camera, while the long-range tests correspond to about 8x–10x. The variation is because we keep the framing (and effective focal length) the same, but different smartphones have slightly different native focal lengths and therefore require different Zoom factors to achieve the same effect.

Bokeh

Archos Diamond Omega

25

Having a second camera doesn’t help the Omega much when it comes to adding depth effects for portraits or artistic bokeh. Indoors, depth estimation is generally good, but inconsistencies greatly reduce the usefulness of the feature. Outdoors, it is hard to get the camera to trigger its depth effect and create blur for bokeh, and when it does the result is often very heavy-handed and not pleasing.

Even at its best, the Omega’s bokeh effect is inconsistent. Here you can see that some portions of the background are blurred, while others are sharp.

In this image of the same scene, the inconsistencies in the background are even more pronounced.

Below are comparison images of the same scene taken with the Omega, the iPhone 7 Plus, and the Nokia 8, all set to Portrait mode. You can easily see how the Omega effect looks unreal compared to the other two. For example, portions of the apartment building are nearly as sharp as the subject’s head, while some closer sections are blurred much more:

Omega image in Portrait mode.

Apple iPhone 7 Plus image in Portrait mode.

Nokia 8 image in Portrait mode.

Video scores explained

The Omega isn’t as strong in Video as it is for photos, turning in a set of merely okay sub-scores in categories other than autofocus. Specifically, it scored: Exposure (72), Color (73), Autofocus (88), Texture (44), Noise (67), Artifacts (66), and Stabilization (56).

As with still images, the Omega exposed video clips well, including high-dynamic-range test scenes — although sometimes it tended to render outdoor scenes a little darker than ideal. Autofocus was also fast and accurate. Noise was well-controlled in outdoor scenes, but color shading was evident. Video clips suffered from artifacts, especially aliasing and ringing. Also, the default video mode doesn’t provide any stabilization.

Conclusion: Decent camera, but doesn’t challenge the best

For casual photographers, or anyone who doesn’t feel they need the very best image quality from the latest flagship phones, the Archos Diamond Omega does a competent job under most typical shooting conditions. Images don’t stand up to close scrutiny, though.Fast autofocus and accurate exposure make it attractive for capturing action or fast-moving scenes, while color issues and artifacts won’t appeal to those trying to make the most of their landscape or travel photos. Its video strengths and shortcomings parallel those for still images, with quick and accurate autofocus once again its biggest strength. Note that it’s quite possible that there will be continued improvement in some areas involving image processing, such as zoom and bokeh, through future firmware updates.

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