Camera displays serve as the core interactive interface of a camera, undertaking critical functions such as live view, image composition, playback, and image evaluation. Differences in screen design across various camera brands and models directly determine the shooting experience and the accuracy of image assessment.
1. Display Size
Definition: Refers to the physical length of the screen's diagonal, measured in inches (1 inch = 2.54 cm).
Mainstream Specifications: Consumer cameras generally use 3 inches as the standard, with differentiated sizes such as 2.7 inches (entry-level models) and 3.2 inches (high-end models).
Impact: A larger size provides a more comfortable visual experience for framing and playback, but it also affects the portability of the camera body.

2. Display Resolution and Pixels
① Resolution: Refers to the actual number of pixels arranged on the screen, expressed as horizontal pixels × vertical pixels. It is the core metric for measuring screen clarity.
② Pixel: The smallest independent unit of imaging.
③ Subpixel: Each pixel consists of three R/G/B subpixels, which are responsible for light emission and color rendering.
The resolution of a display varies with screen size. Suppose a camera screen has 230,000 to 2,359,000 “dots”; the “dots” mentioned here are not pixels, but subpixels. In a display structure, a complete pixel is generally composed of three R, G, and B subpixels.
For example, if a camera display has 921,000 subpixels, the corresponding number of actual pixels is 307,000.

The more pixels there are, the higher the theoretical resolution of the screen. However, the actual perceived clarity by the human eye is also affected by the screen size and viewing distance. The physical size of a pixel is determined jointly by the screen size and the total number of pixels: for a given screen size, the greater the total number of pixels, the smaller the size of each individual pixel, resulting in a finer image with less visible grain.
In the three examples, the screen size is 150×150 mm. As the number of pixels increases from 100 to 10,000, the individual pixel size shrinks from 15×15 mm to 1.5×1.5 mm, significantly improving the fineness of the image.

3. Pixel Size
Pixel size is the physical dimension of a single pixel, determined jointly by the screen size and the total number of pixels. The core rules are as follows:

• For the same display size, the more pixels, the smaller the pixel size;
• For the same number of pixels, the smaller the screen, the smaller the pixel size;
• For the same pixel size, the larger the screen, the greater the number of pixels.

As seen in the figure above, with the same number of pixels (100): the smaller the screen size, the smaller the pixel size (left vs. middle); with the same pixel size (10×10 mm): the larger the screen size, the more pixels it can accommodate (middle vs. right).

4. Pixel Density (PPI)
PPI (Pixels Per Inch) refers to the number of pixels per inch, serving as a unified standard for screen clarity across different sizes. The higher the PPI, the finer the screen, which is independent of the number of subpixels.
Theoretically, PPI is the core metric for a fair comparison of clarity across screens of different sizes. However, it is difficult to provide an absolutely universal “suitable PPI value.” The core benchmark for determining whether a PPI is sufficient is the visual resolution limit of the human eye: when the PPI exceeds the resolving power of the human eye at a given viewing distance, the eye will no longer be able to distinguish individual pixels, resulting in a fine, grain-free visual experience.

5. Human Eye Resolution
For an observer with normal vision, the resolution of the human eye is typically expressed as 1 arcminute (1/60 of a degree): when the visual angle of two adjacent points relative to the human eye is greater than or equal to 1 arcminute, the eye can distinguish the two points; when it is less than 1 arcminute, the eye perceives them as a single point and cannot distinguish the details.
Based on this visual limit, we can calculate the maximum PPI the human eye can resolve at different viewing distances. At a given viewing distance, the minimum physical distance between two distinguishable points can be calculated using the trigonometric formula (see Equation 1):
$$ \tan\left(\frac{\alpha}{2}\right) = \frac{\text{dot pitch}(d/2)}{\text{viewing distance}(A)}\tag{1} $$ Taking the common viewing distance of 11.8 inches (approx. 300 mm) for camera screens as an example:
Settings: Human eye resolution angle $\alpha = 1$ arcminute ($1/60^\circ$), viewing distance $A = 300\ \text{mm}$.
Calculate dot pitch: $a = 2 \times A \times \tan(\alpha/2)$
Substitute values: $a = 2 \times 300\ \text{mm} \times \tan(1/120^\circ) \approx 0.09\ \text{mm}$
This means that at a distance of 11.8 inches, two points must be at least 0.09 mm apart to be distinguished.
Convert to PPI: Convert the minimum dot pitch to the number of pixels per inch (25.4 mm): $25.4\ \text{mm} \div 0.09\ \text{mm} \approx \mathbf{282\ \text{PPI}}$
Conclusion: At a viewing distance of 11.8 inches, 282 PPI is the critical pixel density resolvable by the human eye. Therefore, if the screen PPI < 282, the human eye can clearly see pixel grain; if the screen PPI $\ge$ 282, the human eye cannot distinguish individual pixels.

Factors Affecting Pixel Density:
The level of pixel density is not absolutely good or bad; its practical value is determined jointly by the human eye's resolution limit and the viewing distance: the better the vision and the closer the distance, the higher the required pixel density; the poorer the vision and the farther the distance, the lower the pixel density is sufficient.
As shown in the figure below, the resolving power of the human eye is directly determined by visual acuity, and the two are inversely proportional: Visual Acuity = 1 / Minimum Angle of Resolution (arcminutes).
Normal vision (Visual Acuity = 1): Corresponds to a minimum resolution angle of 1 arcminute, which is the baseline for calculating the limit PPI of the human eye;
Low vision (Visual Acuity = 0.5): Corresponds to an expanded resolution angle of 2 arcminutes. The human eye cannot resolve finer details, so the requirement for screen pixel density (PPI) is lower, and a low-PPI screen can still provide a good visual experience;
High vision (Visual Acuity = 2): Corresponds to a reduced resolution angle of 0.5 arcminutes. The human eye can perceive finer details, so the requirement for PPI is higher, necessitating a screen with higher pixel density to avoid graininess.
Meanwhile, viewing distance also directly affects the resolution limit of the human eye:
At a standard viewing distance of 30 cm (11.8 inches), the limit PPI for the human eye with normal vision is 282. Beyond this value, further increases in PPI offer no noticeable improvement for average users;
At a close viewing distance of 20 cm (7.9 inches), the limit PPI for the human eye increases to 437, and the fineness advantage of high-PPI screens becomes apparent.