IMAGE DISPLAY QUALITY
What Factors Control the Quality of the Image Display?
The image display quality of a digital frame largely depends on the screen resolution, the aspect ratio, the brightness and contrast controls, the color depth of the frame, the viewing angle, the type of screen backlighting display and the screen surface offered by the manufacturer.
The screen resolution of a digital frame is one of the most important features that determines its image display quality.
A higher screen resolution will reproduce better images of higher quality.
The display of a digital photo frame is measured by the number of image pixels the screen is capable of displaying. A pixel (or picture element) is the smallest item of information or a single point in an image.
Pictures are displayed by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels actually seem to be connected because they are so close together.
The image display quality of a digital frame not only depends on the resolution and how many pixels it can display but also on how many bits are used to represent each pixel. This determines the number of colors or shades of gray that can be displayed.
The resolution of most current laptop and PC monitors is set between 800 x 600 pixels (480,000) and 1024 x 768 (786,432) pixels. These numbers represent the display on a computer screen of anywhere from 14" to 21."
It makes sense that a 10" digital frame with a screen resolution of 800 x 600 (480,000) will have greater resolution when compared to the larger computer display screens (14" to 21") with the same resolution! Greater resolution equals better image display quality.
Be careful not to confuse screen size with frame size. Most digital frames have smaller screens encased in larger frames.
Whatever frame is chosen, NEVER settle for a screen resolution below 640 x 480 pixels (307,200) (for frames 7" and above), no matter what the price may be! Don't bargain for poor image display quality.
A majority of digital picture frames will automatically resize your digital image to within a normal browser window so you won't have to scroll up or down to see the entire photo. This is a feature that can greatly enhance the image display quality.
Image resizing can dramatically increase the amount of images that can be saved to the internal memory. Software can be purchased that will optimize your photos to match the screen resolution of your frame. This will also result in a larger number of photos that can be stored either on a memory card or the frame.
There are many image resizing programs that can be downloaded from the Internet. You may also use specific digital photo frame image programs such as ACDSee Picture Frame Manager and resize all your photos. This will save a lot of space and there will not be a visible difference in the image quality.
Another option is to resize photos through photo editing software such as Photoshop or Lightroom. Be aware that there have been compatibility issues with pictures altered in some versions of Photoshop. If you have a problem with those versions, a JPEG should be saved as “Save for Web”. In the preview window, un-click “progressive” in JPEG export properties, but leave the “optimized” checkmark on. It may also help to put the quality slider to 100.
Please note that when transferring photos from a Mac, the DOS Fat formatting of the internal memory cannot store a lot of photos in one transfer. The photos may have to be separated into files or folders to use all the memory. Transferring photos from a Mac may best be done one at a time.
The aspect ratio represents the relationship between an image's height and width.
As a rule, digital frames come in one of two aspect ratios, 4:3 or 16:9 (or very close to these numbers).
Since most digital cameras take photos in the 4:3 aspect ratio, a frame with an aspect ratio of 4:3 may be your best bet to fit your photos.
Frames with aspect ratios of 16:9 may crop a piece of the top and bottom of your photos in order to display the image on the screen. This could lead to poor image display quality.
However, for those purchasers who are looking for the effect of a widescreen feel (especially in landscapes), the 16:9 aspect ratio may actually make more sense!
These wider screens can make the digital frame look and feel like a mini HDTV!
The Relationship Between Screen Resolution and Aspect Ratio
Screen Resolution and aspect ratio are really just 2 different ways of expressing the same thing. The aspect ratio is actually the simplified fraction of the screen resolution. Reducing the screen resolution figures to a fraction will result in the aspect ratio. For example, an 800 x 600 screen resolution will reduce down to 4:3.
Since the aspect ratio of most digital frames will be either 4:3 or 16:9 (or close), a simple way to determine the ratio of a specific digital frame is that a 4:3 aspect ratio results in a square frame where the 16:9 more closely resembles a rectangle.
Below are examples of common abbreviations for some of the screen resolution sizes that can be found on digital frames as well as on computer and TV monitors: (Any of the first 5 can be found in most digital frames today.)
QVGA (quarter-video graphics array) (320 x 240)
VGA (video graphics array) (640 x 480)
WVGA (wide video graphics array) (800 x 480)
SVGA (super video graphics array) (800 x 600)
WSVGA (wide super video graphics array) (1024 x 600)
XGA (extended graphics array) (1024 x 768)
WXGA (wide extended graphics array) (1280 x 800)
SXGA (super extended graphics array) (1280 x 1024)
UXGA (ultra extended graphics array) (1600 x 1200)
WSXGA+ (wide super extended graphics array)(1680 x 1050)
WUXGA (wide ultra extended graphics array) (1920 x 1200)
WQXGA (wide quad extended graphics array) (2560 x 1600)
For the best image display quality, it is always preferable to choose a frame that allows the user to control the brightness and contrast of the screen.
The contrast is the ratio of the white (brightest color) to that of the black (darkest color) that the system is capable of producing.
The higher the ratio, the better the darks will appear in the photos.
Too low of a ratio will cause the photos to look washed out.
Choose as bright a screen as possible while keeping a high contrast ratio such as 300:1, which is good, or 400:1, which is excellent. This will produce a higher standard of an image display quality.
Of course, it should be obvious that the more colors that are available, the better the image display quality will be.
As discussed above under Screen Resolution, the image display quality depends on the screen resolution and how many pixels it can display.
The image display quality is also affected by depth of the color. The number of bits used to represent each pixel is what determines the number of colors and shades of gray that can be displayed on a screen.
An 8-bit display allows for 256 different colors or shades of gray and 24-bit color systems can display more than 16 million different colors. Screens that support a 30-bit or higher display are the most ideal.
The Viewing Angle
It can be quite a disappointment after carefully editing and transferring pictures to a frame to realize one must stand directly in front of the frame in order to satisfactorily view the images.
Select a frame that can display images from all different angles when viewed in order to get the best image display quality.
For any frame other than smaller, portable ones, do not accept less than a 65 degree viewing angle to assure that your images can be enjoyed from anywhere in the room.
For this you will need to make sure you have a TFT LCD screen display.
Screen Backlighting Displays
Most TVs and digital frames come with LCD (Liquid Crystal Display) panels for their screens. A backlight source is needed for a viewer to see images displayed on the screen.
LCDs emit CCFL (Cold Cathode Fluorescent Lamp) or Fluorescent light. This backlight source can be found at the rear of the panel. LCD technology was a major improvement over the old TV displays known as CRT or Cathode Ray Tubes.
Some frames use LCD panels that are recycled versus new digital panels, or they use analog, rather than digital. This can affect the image display quality. The quality will be much better with new digital LCD panels.
TFT stands for Thin Film Transistor. When used with LCDs or Liquid Crystal Displays, it improves the image display quality of small font displays so they do not appear fuzzy or jagged.
Another feature of TFT LCDs is that they project a picture up to an 80 degree viewing angle. An LCD only gets to about a 45 degree. TFT also produces a sharper image.
An active matrix display contains polarizing sheets and cells of liquid crystal and a matrix of thin film transistors to make a TFT-LCD.
The terms “active matrix” and "TFT” or “thin film transistors” are often used interchangeably because thin film transistors are common components in an active matrix display (though some designs use other components such as diodes).
These thin film transistor devices have the ability to hold a charge for a limited period of time. They store the electrical state of each pixel on the display while all the other pixels are being updated. Thus only the desired pixel receives a charge. The pixel acts as a capacitor to hold the charge until the next refresh cycle.
A much brighter, sharper image display quality is possible with an active matrix display than on a passive matrix of the same size, since a passive matrix display just uses a simple conductive grid to deliver current to the liquid crystals in a target area.
As stated above, an active matrix TFT LCD display also has a much large viewing angle.
STN and CSTN
STN is a type of LCD display. The color version is called CSTN. This type of display technology can usually be found on lower end devices such as digital keychains. CSTNs typically produce a poorer image display quality and response time than a TFT LCD but are much cheaper to produce and more energy efficient.
When LED or Light Emitting Diode technology is used with an LCD panel, the LCD displays are backlit with multiple lights placed all around the panel.
The result of using LED is that panels can be much slimmer and the technology produces a much wider range of colors than traditional LCD/CCFL technology.
Even more important, the LED backlighting uses less power, produces less heat and comes to full brightness much more quickly. And the good news for the environment is, it is less toxic than the mercury-filled fluorescent bulbs.
A severe shortfall between supply and demand of LEDs (light-emitting diodes) is expected in the near future. A strong consumer demand for LED backlit large-screen LCD TVs, which use an average of 300 to 500 LEDs per panel, has been instrumental in producing this shortfall.
LED usage has also increased for devices with smaller screens, including laptops, which use around 50 LEDs, monitors, (using approximately 100 LEDs), mobile phones, digital cameras and keyboards, portable navigation devices and, of course, digital photo frames.
Residential, commercial and industrial lighting applications are also showing increased consumption of LEDs. The current total industry capacity to produce LED units has not kept up with the demand and many LED manufacturers operate at nearly 100 per cent capacity levels.
The solar industry, on the other hand, has an oversupply of solar panels due primarily to low module prices. The thin-films used in both the solar and LED panels can be used in both industries. The solution to the shortfall problem in the LED industry may be resolved if the solar panel manufacturers would shift their manufacturing emphasis to include manufacture of LEDs as well.
OLED (Organic Light Emitting Diode) screens are one of the latest innovations in TVs and digital frames.
A single pixel on a color LCD is made of three colored elements, ordered as blue, green and red (BGR) or as red, green and blue (RGB). These are sometimes referred to as sub-pixels. They actually appear as a single color to the human eye because of the mechanics of the nerve cells in the eye.
In a LCD screen which has LED backlighting, the LED provides a white light source which is filtered through a color LCD matrix to produce a picture. Any sub-pixel on a LED-backlit screen is actually controlled by the LCD matrix.
In an OLED screen, each of the sub-pixels has its own light and the brightness is controlled by the brightness of the light. The result of using this technology is the vividness of the color reproduction and the amazing detail and contrast leading to very high image display quality. In addition, with OLED there are no viewing angle limitations or response time issues either.
Lower power consumption and flexible screens are some of the advantages of OLED. Major drawbacks at this time include the prohibitive cost of mass production and the limited lifespan of this light source.
Electronic products already in the marketplace which feature OLED technology, such as some digital frames and large screen TVs have proved to be far too expensive for the general consumer.
On the other hand, OLED technology is being used successfully in the smaller display screens of many hand-held electronic devices manufactured today. These include cell phones, cameras and MP3s. The efficiency of OLED technology really stands out in the small displays of these devices.
As OLED technology expands, it is inevitable that its drawbacks will be addressed. Even now there are technologies developing such as PHOLEDs, which utilize phosphorescence to make OLEDS more efficient. LPDs (Laser Phosphorescent Displays) use lasers to stimulate the phosphors that produce the images on a screen which could cut energy consumption by as much as 75%!
In early 2010, the Samsung 700Z, a more affordable digital photo frame which utilizes active matrix OLED (AMOLED)technology was introduced. The 7” screen, enclosed in an extremely thin frame, can display photos, audio and video with an impressive 1024 x 600 screen resolution and a viewing angle as wide as 180 degrees! This is image display quality at its best!
Unfortunately, Samsung no longer makes the 700Z digital photo frame. However, Samsung makes use of AMOLED technology in its latest mobile smart phones.
Sony has developed an ultra thin, durable and flexible OLED display which will allow for thinner, lighter and more durable mobile media devices than ever before.
Sony's super flexible full color OLED display can be wrapped around a thin cylinder. This is the first OLED panel which is capable of reproducing moving images while being repeatedly rolled up and stretched around a cylinder with a radius of only 4 mm!
OLEDs in the Future
In the not-too-distant future, we may expect to see OLEDs being utilized in more and more digital frames, TVs, hand-held devices, computer monitors and notebook screens, video games and even clothing!
This feature also affects the image display quality of a digital frame and can easily be missed by the first-time buyer.
Is the screen of the digital photo frame under a piece of glass or does it have a non-reflective screen? If it is glass, the glass itself can create a bit of a glare, taking away from the image display quality of the screen.
The screen of the digital frame can get scratched or broken and should receive the same care as that of a computer screen. This is very important, especially if your digital frame has a touch screen menu interface.
For this reason, use only a soft, non-abrasive cloth such as a camera lens cloth to clean the screen.
MOST IMPORTANT: DO NOT APPLY ANY CLEANING LIQUID DIRECTLY TO THE LCD SCREEN! Just clean the screen with a moistened cleaning cloth.
Top of Image Display Quality of Digital Frames
Back to Display Options of Digital Frames
Back to Styles of Digital Frames
Back to Choosing Digital Frames
Back to Home Page
METHODS of CONNECTIVITY for TRANSFERRING IMAGES for DIGITAL FRAMES
PICTURE FUNCTIONS of DIGITAL FRAMES
ADVANCED FEATURES of DIGITAL FRAMES