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Problem

Displays are the most critical output on modern smartphones, as well as a highly touted feature. Even minor degradations in performance can render the display uncomfortable to use, unreadable, or reduce the perception of the quality of the display.

Automatic light sensors and user controlled display settings are difficult to find, difficult to use, and often cannot be made to yield an appropriate light level without significant user input.

Solution

This pattern focuses on higher quality color displays, with light sensors suitable for use setting automatic brightness. Other display types may use many of the components of the patterns, but may not be able to meet all of them. This also presumes backlit screens; lit-pixel screens such as OLED (and AMOLED) screens may have to modify the technical information to achieve the intended result.

Users must be able to get to display settings easily, preferably without much on-screen interaction, in case the screen is hard to read and they need to adjust it. The primary display setting is brightness (white point). Contrast (black point) and other controls may also be provided, but will not be well understood by the typical user; good median values must be selected by default for all other display adjustments.

Automatic sensors must be calibrated correctly, to take into account they are viewing the user's face, at typical mobile use distances. Do not calibrate on neutral gray at infinity.

The user must be able to make manual adjustments even if an automatic setting is provided, and should be able to provide user input to the automatic settings, and provide user calibrations to the light sensor.

Variations

Manual is the most common mode, available on almost all devices with a screen. A simple one-axis user control is provided.

Modern mobile devices with high quality screens mostly come set to automatic mode by default. While in automatic, a light sensor detects the user's face and surmises ambient light level to determine the optimal output. The manual mode may be switched to which disables the automatic settings.

An automatic mode with manual input should be provided, to allow user modifications to any failure of the automatic system to detect the optimal output level.

A learning mode would be a useful fourth variation, using the principles of learning user predictive text, voice or gestural input. The device will monitor user overrides to automatic input and/or accept multiple user calibrations in order to adjust how automatic behaviors work, with the intent of an entirely satisfactory automatic behavior, eventually.

Interaction Details

Ideally, a direct input method should be available, so the user can change brightness without looking at the screen or selecting functions that may be difficult to see if the screen is far too bright, or far too dim. A well-used option is to have an existing function (such as volume or power) make a general settings panel appear, with brightness, volume, synch and power-off/restart functions. Once it appears, volume keys may change the volume, and (for example) the Left and Right keys may change brightness. Other solutions may be more suitable to the specific interface or operating system.

The primary brightness adjustment control is a slider, or similar control with implied analog input. In fact, this will control input in steps based on the software controlling the display backlight. Allow direct numeric input of these values. Interactive methods from the Spinner pattern may be useful here.

The brightness control must allow setting true minimum and maximum output. Mobile devices can be used in complete darkness, where users eyes may be fully adjusted, or bright screens may distract others. Do not select an arbitrary minimum brightness above the adjustment range value of 1.

A simple setting on the brightness control panel must allow enabling and disabling of the automatic brightness control. This may be set from other places as well.

A function should be provided to add user-adjustment to auto-brightness. This will not disable automatic control, just add the user control as a new temporary zeroing point. Ideally, the device will remember this user setting and factor it in over time in a learning mode.

Sensors will continue to be most usefully places on the front of the device (among other things, it is probably best for checking light where the user is). Calibrate sensors not to neutral gray, but to people's faces at typical distances. Provide a function to allow users to recalibrate the sensor to their face and typical viewing angle and distance. This may also be implemented as an explicit learning mode, with the user performing this for several typical environments in which they use the device.

Presentation Details

Whenever room is available in the Annunicator Row, in a Notification Strip or in similar areas where current settings are displayed, the current brightness settings should be displayed. This should indicate automatic or manual, and the level in the conventional scale of measure used on the adjustment panel itself.

Within the brightness panel, it must be very clear when automatic brightness is enabled. When enabled, display the actual brightness selected by the automatic controls in a manner similar to the manual setting.

When adjusting brightness, the screen must reflect the adjustments in real time, so the user can tell how bright they want it. Do not set then commit to change brightness.

It is highly suggested that adjustments be simulated when the brightness panel is displayed. This is so the adjustment panel itself can be seen in all conditions. Set the screen backlight to 100% brightness, with the adjustment panel as a modal Pop-Up where the sliders and instructions simulated (via the pixel color) to 50% brightness, with very high contrast, such as white letters and outlines on a black background. The parent window behind the Pop-Up will simulate (with color changes to the pixels themselves or opacity to a black overlay...) the adjusted-to value.

Within the display adjustment panel, present the brightness numerically as well as via any sliders, dials or other graphical presentation. Some users will understand numerical values better, and most users will be able to recall numerical values that work in certain environments, so may be able to adjust to those by memory if automatic systems do not work.

Antipatterns

Avoid brightness changing functions that are not discoverable or learnable.

Do not overly simplify the brightness control software (either automatic or manual) by limiting to a small number of large steps. With even 16 steps, users can detect the difference between individual steps. They may not find a suitable brightness, or may find the display jumps settings (exhibits "seeking" behavior) when in automatic mode. Using the full complement of steps (100 or 256, for example) will provide sufficient levels and smoothness that even rapid adjustments will be perceived as smooth changes in brightness.

Examples

DISCUSS: This article at Gizmodo is pretty darned good, and point out that the issues with current devices are not whiny, or individually-perceived, but truly bad. ALSO note that the above are by no means my pie-in-the-sky hopes for better interfaces. I have seen most of these, often with things like monochrome GPS, remote controls and other very old devices. High end ones need to get better at this. And everyone needs to understand how interactive design can go a long way towards solving this, it's not a hardware problem! - SSH

Display Brightness Controls (last edited 2011-08-01 00:09:18 by shoobe01)