A Buyer's Guide to Digital Picture Frames
Contrast Ratio and Brightness
The contrast ratio and brightness denotes how well colours are represented on the screen.
Contrast Ratio is a measurement of how bright white is represented compared to black. This is shown as 300:1 which means white is 300 x brighter than black. In theory you would be looking for a digital picture frame with a higher contrast ratio so detail in shadows and bright areas of your photos are not lost. In reality different manufactures make this measurement in different ways and conditions. So you may as well ignore the contrast ration when comparing digital picture frames. OLED picture frames are able to display more colours than a LCD display so will preserve the detail of your photos in these areas.
Brightness is how bright the display is, measured in CD/M2 (candela per meter square) or Nits which is equal to 1 CD/M2. For LCD displays this is typically between 250 and 350 CD/M2. If you intend on locating your picture frame in a well lit location then you will need a frame with a higher brightness rating, especially if it will be in direct sunlight. For digital picture frames located in darker locations the brightness rating is less important as you may even wish to turn the brightness down in some cases.
OLED display emit light so they will be viewable in much brighter conditions than a LCD display that work by blocking light.
Wide screen 16:9 and Standard 4:3
The aspect ratio is the measurement of how many horizontal
pixels there are compared to vertical pixels. So for the 16:9 aspect
ratio for every 16 horizontal pixels there are 9 vertical.
In the real world 4:3 is equivalent to normal TV and 16:9 is equivalent to wide screen. Some frames have a wide screen aspect ratio of 15:9 or 16:10.
The majority of digital cameras have an aspect ratio of 4:3 or 3:2 so it would make sense to have a 4:3 digital picture frame. For some reason most frames either only display in 16:9 or are capable of displaying the 16:9 format. When you view a 4:3 picture on a 16:9 frame one of three things happen:
- The photo is shown at the 4:3 aspect ratio and two thick black borders are shown either side of the photo to fill in the blank area of the display.
- The picture is the correct height but the width is stretched to fill the screen. This is how a wide screen TV deals with a the same problem. In most cases this is acceptable but does add a few pounds in weight to everyone.
- The width of the photo is correct but the top of the bottom of the picture is cut off. Unless you are related to the headless horseman this is not that useful on closeup photo's but could be if you had scary hair that day.
If you do have photos in the 16:9 format and they are displayed on a 4:3 digital picture frame then the opposite happens:
- The photo has the correct width but the black boarders are above and below the photo making the image small.
- The height is correct but the width is squeezed so everyone looks tall and skinny. If you are tall and skinny you may well disappear.
- The height is correct but the width is cut down to a 4:3 format sized picture. So make sure the ugly people and embarrassing aunt Betty are standing at the sides in the family group shots.
LCD displays are made up from pixels which together make up the resolution of the display and each pixel contains 3 sub pixels. 1 for red 1 for green and 1 for blue. For a digital picture frame with a resolution of 480 x 234 there are a total of 336,960 sub pixels. Large screens will need millions of sub pixels to make up the display. Each sub pixel has a filter that effectively opens and closes to let the correct amount of light through for the level of colour required for that pixel to display it's part of the photo. A dead pixel is common term to describe when 1 or more of the filters are not working. This is seen by either a constant bright spot on the screen or a constant black spot. If a single sub pixel is faulty then you will see a dot of red, green or blue usually when that area should be dark. These are referred to as stuck pixels.
As manufactures are reluctant to scrap a whole display due to one or two faulty pixels they have set a tolerance of how many dead or stuck pixels they will allow on a screen. For the consumer this a faulty product. If you are lucky you can return it to the store but as soon as you mention a dead pixel you are likely to be referred to the manufacturer who may or may not replace the picture frame depending on their policy. This is not just an issue with cheaper brands but all manufactures and it is also a problem with computer monitors and TV's.
I don't want you to think you are likely to get a dead pixel as I'm sure the manufacturing process is improving all the time and as digital picture frames have considerably less pixels than monitors and TV's, it may well be less of an issue. Ideally ask to have a demo of the actual digital picture frame you are buying, not the display model, and check it before handing over your cash. If you buy online then you can use the Distance Selling Regulations which gives you a 7 day cooling off period to return your goods in the UK. http://www.oft.gov.uk/advice_and_resources/resource_base/legal/distance-selling-regulations/
If you have a digital picture frame with a dead or stuck pixel then please let me know the make, model and what reaction you have had with the store or manufacturer. I will then list the results to see if there are any manufactures to avoid. Likewise let me know if you have a good display and I will show that as well.
The most common picture format used with consumer digital
cameras is Jpeg. Though it is not the best format to save your photos
in, it does have a small file size in comparison to other formats,
which allows you to fit more photos on your memory card. Being that
Jpeg is a widely used format it is the image file type supported by all
digital picture frames, but is not the only one.
So what is the difference?
Jpeg (jpg) is a lossy image format. What this means is some of the detail of the picture is lost every time the picture is saved. The amount of detail that is lost is based on the compression level. At 100% some quality is lost but is barley noticeable depending on the picture. At 10% your lovely portrait photo might as well be subtitled "identity has been hidden for legal reasons". The reason for this is to make the file size as small as possible allowing you to store more photos on a memory card at the cost of acceptable quality loss. If you know you want to edit your photos and your camera supports it then choose a different format.
Digital picture frames are designed to use Jpeg images created by digital cameras. Some Jpeg files created on a computer may not work on a picture frame like Jpeg files saved using the progressive option or the Jpeg2000 format though this is not a commonly used format.
Raw is the pure data from cameras light sensors. What usually happens when a photograph is taken is the pure image data is processed, taking into account the cameras settings for lighting and colour, and converted to Jpeg losing some quality along the way. The Raw format is literally that, the raw image the sensors captured with no processing, this gives a professional photographer full control over how the photo should look when processed on a computer. It is unlikely that the average user would use this format.
There are several different versions of the Raw format, so when you see a digital picture frame advertised as using Raw images, it is most likely that it will be from the same branded cameras. For example, Sony digital picture frames can only use Raw images from some Sony digital cameras.
Tiff (tif) is a loss less image format commonly used in desktop publishing. Photographs saved in the Tiff image format will be better quality than Jpeg and should be used by the average user who intends on editing the photograph. Tiff uses compression but unlike Jpeg images no quality is lost so the file size will be larger and fewer photographs can be stored on a memory card.
Digital picture frames are designed to use Tiff files created by digital camera so some Tiff files created with some computer programs may need to be converted before they can be used with a picture frame that supports Tiff files.
BMP is an image format commonly used on Windows operating systems. I'm not aware of any digital cameras using the BMP format but some digital picture frames do. This is mainly intended for pictures produced on a Windows computer to be displayed on a picture frame. BMP is also a loss less image format so can be used when a picture needs to be edited or kept at full quality.
Some digital picture frames can play video files that have been recorded by a digital camera, mobile devices or video camera that uses memory cards. Digital cameras and mobile devices record video in different formats such as AVI, Mpg, Mpeg4, Mov, Mjpeg, Wmv, DV. Each format has it's advantages and disadvantages but are either used for compatibility, quality or file size.
As digital picture frames are primarily designed to show still images, their support for video files , if any, are limited so check that the frame supports the same format as your digital camera or mobile device. Though you can convert any video file to another format using a computer with the right software.
Don't expect high quality playback especially from smaller frames as they are best used to review digital camera video conveniently on a bigger screen than the cameras rather replacing playback on a computer. Also the speakers on picture frames tend to be small and tinny.
Computers can use many different video files differing in quality and size. Though you are likely to have video in formats that are compatible with digital picture frames it is possible that they will not work with a picture frame due to the various ways these files can be saved.
Some picture frames can play MP3 music files that can be used as a backing track to your photos and enhance the memories of your holiday snaps. As the speakers are usually small don't expect great sound quality, though you could use the earphone socket and connect external speakers.
Exif data is information stored by a digital camera about the
settings used when the photo was taken. For example the cameras model,
date, time, exposure, flash mode, picture mode, orientation....
This information is stored as part of the Jpg and Tiff file formats. Digital picture frames that use this information can display parts along with the photo. Frames that have Auto Rotate option use the orientation information to display the photo the correct way round.