Crosscall Stellar-X5 Camera test

For scoring and analysis, SBMARK engineers capture and evaluate more than 2,600 test images in both controlled laboratory environments and natural outdoor, indoor, and low-light scenes, using the camera’s default settings. The photography protocol is designed to take into account key use cases and is based on typical shooting scenarios, such as portrait, family and landscape photography. Evaluation is performed by visually examining images Cons a natural scene reference and performing objective measurements on laboratory-captured graph images under varying lighting conditions from 1 to 1,000+ lux and color temperatures from 2,300K to 6,500K.

Exposure is one of the key attributes for technically good images. The main attribute evaluated is the brightness of the main subject across various use cases such as landscape, portrait or still life. Other factors evaluated are contrast and dynamic range, e.g. the ability to make details visible in both bright and dark areas of the image. Repeatability is also important because it demonstrates the camera’s ability to provide the same rendering when shooting multiple images of the same scene.

Color is one of the key attributes for technically good images. The image quality attributes analyzed are skin tone rendering, white balance, color shading and repeatability. Regarding color and skin tone rendering, we penalize unnatural colors but respect the manufacturer’s choice of color signature.

Autofocus tests focus on focus accuracy, focus repeatability, shutter lag, and depth of field. Shutter delay is the difference between when the user presses the capture button and when the image is actually taken. It includes focusing speed and the device’s ability to capture images at the right time, the so-called “zero shutter lag” capability. While a shallow depth of field can be nice for single-subject portraits or close-ups, it can also pose a problem in some specific conditions such as group portraits; Both situations are tested. Focus accuracy is also evaluated in all real-world images taken, from infinity to close-up objects and low-light conditions to outdoors.

Texture tests analyze the level of detail and texture of subjects in images taken in the lab and in real-life scenarios. For natural shots, special attention is paid to the level of detail in the light and dark areas of the image. Objective measurements are performed on map images taken under various lighting conditions from 1 to 1000 lux and different types of dynamic range conditions. The papers used are the proprietary SBMARK (DMC) paper and the Dead Leaves paper.

Noise tests analyze various noise attributes such as intensity, chromaticity, grain, texture on real-life images and on graph images taken in the laboratory. For natural images, particular attention is paid to noise on faces, landscapes, but also on dark areas and high dynamic range conditions. Noise on moving objects is also evaluated on natural images. Objective measurements are performed on graph images taken under various conditions from 1 to 1000 lux and different types of dynamic range conditions. The graph used is the dead leaf graph and standardized measurement such as visual noise derived from ISO 15739.

Artifact evaluation examines lens shading, chromatic aberrations, geometric distortion, ringing edges, halos, ghosting, quantization, unexpected changes in color hue, among other types of possible unnatural effects on photo. The more severe and frequent the artifact, the greater the point deduction from the score. The main artifacts observed and the corresponding point loss are listed below.

SBMARK engineers capture and evaluate more than 400 test images in controlled laboratory environments and in natural outdoor, indoor, and low-light scenes, using default camera settings and pinch zoom at various zoom factors from ultra wide zoom to long range zoom. The evaluation is performed by visually examining the images Cons a reference of natural scenes and performing objective measurements of map images captured in the laboratory under different conditions from 20 to 1000 lux and color temperatures from 2300K to 6500K.

SBMARK engineers capture and evaluate more than 2.5 hours of video in controlled laboratory environments and natural low-light scenes, indoors and outdoors, using default camera settings. The evaluation consists of visual inspection of natural videos taken under various conditions and performing objective measurements on videos of graphs recorded in the laboratory under different conditions from 1 to 1000+ lux and color temperatures from 2,300 K to 6,500 K.

Exposure tests evaluate the brightness of the main subject and the dynamic range, e.g. the ability to make details visible in both bright and dark areas of the image. The stability and temporal adaptation of the exposure are also analyzed.
Image quality color analysis examines color rendering, skin tone rendering, white balance, color shading, white balance stability and its adaptation when the light changes.

Texture tests analyze the level of detail and texture of real videos and graphics videos recorded in the lab. Natural video footage is assessed visually, paying particular attention to the level of detail in bright and dark areas. Objective measurements are performed on chart images taken under various conditions from 1 to 1000 lux. The cards used are SBMARK (DMC) card and Dead Leaves card.

Noise tests analyze various noise attributes such as intensity, chromaticity, grain, structure, temporal aspects on real video recordings and on videos of graphs taken in the laboratory. Natural videos are evaluated visually, with particular attention to noise in dark areas and high dynamic range conditions. Objective measurements are performed on graph videos recorded under various conditions from 1 to 1000 lux. The graph used is the SBMARK visual noise graph.

The stabilization rating checks the device’s ability to stabilize footage thanks to software or hardware technologies such as OIS, EIS or any other means. The evaluation examines residual motion, smoothness, gel artifacts, and residual motion blur in walk-and-run use cases under various lighting conditions. The video below is an excerpt of one of the scenes tested.

Artifacts are evaluated with MTF and ringing measurements on the SFR graph in the lab, as well as frame rate measurements using the LED universal timer. Natural videos are visually evaluated paying particular attention to artifacts such as aliasing, quantization, blocking, and hue shifting, among others. The more severe and frequent the artifact, the greater the deduction of points from the score. The main artifacts and the corresponding point loss are listed below.