While more than 32 point exist, here are the main ones:
“IMAGE QUALITY”
1. Lens architecture & design
2. Aperture: affecting saturation, low gain SNR, circle of confusion,
etc.
3. File type compression: 10 bit, 12 bit, compression algorithms
4. File type: Raw / jpeg, TIFF, Adobe color space
5. Image demosaicing processing and its corresponding main board algorithms
6. Main board image compression algorithms
7. Native sensor SNR: Silicon wafer design & efficiency
8. Optical low pass filter: if present or not
9. Main board image denoising SNR filtering & efficiency technology
10. Lens efficiency
11. Microlens design & efficiency
12. Pixel pitch
13. Lens LPMM resolving power
14. Sensor architecture: normal or BSI or other
15. Color Filter Array: Bayer, X-trans etc.
16. Sensor megapixel count and density
17. Lens spectrum transmissive response from near IR to near UV, or all
visible light frequencies
18. Image Saturation, i.e. ETTR & fundamental image exposure
maximization
19. Analog to digital converters
20. Lens microcontrast
21. Sharpness determines the amount of detail an image can convey.
System sharpness is affected by the lens (design and manufacturing quality,
focal length, aperture, and distance from the image center) and sensor (pixel
count and anti-aliasing filter). In the field, sharpness is affected by camera
shake (a good tripod can be helpful), focus accuracy, and atmospheric
disturbances (thermal effects and aerosols). Lost sharpness can be restored by
sharpening, but sharpening has limits. Oversharpening, can degrade image
quality by causing "halos" to appear near contrast boundaries. Images
from many compact digital cameras are sometimes over-sharpened to compensate
for lower image quality.
22. Noise is a random variation of image density, visible as grain in
film and pixel level variations in digital images. It arises from the effects
of basic physics— the photon nature of light and the thermal energy of heat—
inside image sensors. Typical noise reduction (NR) software reduces the
visibility of noise by smoothing the image, excluding areas near contrast
boundaries. This technique works well, but it can obscure fine, low contrast
detail.
23. Dynamic range (or exposure range) is the range of light levels a
camera can capture, usually measured in f-stops, EV (exposure value), or zones
(all factors of two in exposure). It is closely related to noise: high noise
implies low dynamic range.
24. Tone reproduction is the relationship between scene luminance and
the reproduced image brightness.
Contrast, also known as gamma, is the slope of the tone reproduction
curve in a log-log space. High contrast usually involves loss of dynamic range
— loss of detail, or clipping, in highlights or shadows.
25. Color accuracy is an important but ambiguous image quality factor.
Many viewers prefer enhanced color saturation; the most accurate color isn't
necessarily the most pleasing. Nevertheless it is important to measure a
camera's color response: its color shifts, saturation, and the effectiveness of
its white balance algorithms.
26. Distortion is an aberration that causes straight lines to curve. It
can be troublesome for architectural photography and metrology (photographic
applications involving measurement). Distortion tends to be noticeable in low
cost cameras, including cell phones, and low cost DSLR lenses. It is usually
very easy to see in wide angle photos. It can be now be corrected in
software.
27. Vignetting, or light falloff, darkens images near the corners. It
can be significant with wide angle lenses.
28. Exposure accuracy can be an issue with fully automatic cameras and
with video cameras where there is little or no opportunity for post-exposure
tonal adjustment. Some even have exposure memory: exposure may change after
very bright or dark objects appear in a scene.
29. Lateral chromatic aberration (LCA), also called "color
fringing", including purple fringing, is a lens aberration that causes
colors to focus at different distances from the image center. It is most
visible near corners of images. LCA is worst with asymmetrical lenses,
including ultra-wides, true telephotos and zooms. It is strongly affected by
demosaicing.
30. Lens flare, including "veiling glare" is stray light in
lenses and optical systems caused by reflections between lens elements and the
inside barrel of the lens. It can cause image fogging (loss of shadow detail
and color) as well as "ghost" images that can occur in the presence
of bright light sources in or near the field of view.
31. Color moiré is artificial color banding that can appear in images with
repetitive patterns of high spatial frequencies, like fabrics or picket fences.
It is affected by lens sharpness, the anti-aliasing (low-pass) filter (which
softens the image), and demosaicing software. It tends to be worst with the
sharpest lenses.
32. Artifacts – software (especially operations performed during RAW
conversion) can cause significant visual artifacts, including data compression
and transmission losses (e.g. Low quality JPEG), oversharpening
"halos" and loss of fine, low-contrast detail.
