What is «resolution»?
The resolution of a screen is measured in pixels, which are the smallest element that makes up an image. On screens it is expressed as number of pixels horizontally x number of pixels vertically. Therefore, an image with a resolution of 640 x 480 has 640 pixels per line and 480 lines.
The higher the resolution, the more detailed an image can be. The leap in image quality from standard tube TVs to today’s HD and Full HD TVs is partly due to the increase in resolution. On a smartphone, a higher resolution screen improves the readability of the text and also allows you to place more content at once on the screen. When browsing the web, for example, this means that you will have to scroll the page less often.
VGA or Video Graphics Array is a video standard for personal computers created in the 1980s and was the main form of connection between computers and monitors for a long time, until it lost space for standards capable of supporting higher resolutions, such as HDMI. One of its characteristics is the resolution of 640 x 480 pixels, which by analogy became known as «VGA resolution».
From the 2000s on, smartphones and other mobile devices whose screens had this resolution began to appear, which is why they became known as «VGA screens». But there is a whole «family» of resolutions that takes the 480 lines of the VGA as a reference.
One of them is the QVGA (Quarter VGA), which has 320 x 240 pixels, or a quarter (hence the name) of a VGA screen. An example of a device that uses this resolution is the Sony Xperia X10 mini smartphone. WQVGA (Wide QVGA), is a «widescreen» variant, with a resolution of 400 x 240 pixels.
The VGA resolution itself has a «Widescreen» variant, WVGA (Wide VGA), with 800 x 480 pixels. It was used, for example, on Google Nexus One and Samsung Galaxy S devices.
At this point, it is convenient to remember that all these resolutions usually have small variations to suit the aspect ratio (ratio of width to height) of a device. WVGA, for example, can be 720 x 480 pixels to suit a 16:10 aspect ratio screen. The list below shows a summary of VGA resolutions, including some variations not mentioned here:
List of VGA-based resolutions
|VGA||640 x 480 pixels|
|WVGA||800 x 480 pixels|
|FWVGA||854 x 480 pixels|
|QVGA||320 x 240 pixels|
|QQVGA||160 x 120 pixels|
|HQVGA||240 x 160 pixels|
|WQVGA||400 x 240 pixels|
|HVGA||480 x 320 pixels|
|WVGA||800 x 480 pixels|
|SVGA||800 x 600 pixels|
|DVGA||960 x 640 pixels|
|WSVGA||1024 x 600 pixels|
XGA and variations
XGA or Extended Graphics Array appeared in the 90s as a complement to the specifications of the VGA and Super VGA. Regarding resolutions, the name usually means 1024 x 768 pixels, which for a long time was the most common resolution on 4: 3 screens on PCs. XGA also had «wide» variations, collectively known as WXGA (Wide XGA):
- 1152 x 768 pixels.
- 1280 x 720 pixels.
- 1280 x 768 pixels.
- 1280 x 800 pixels.
- 1360 x 768 pixels.
- 1366 x 768 pixels.
The Google Nexus 4 is an example of a smartphone that uses a WXGA resolution, in this case 1280 x 768 pixels. There is also a variant called XGA + that represents the resolutions of 1152 x 900 and 1152 x 864 pixels. The following is a summary of all (or almost all) XGA variations:
List of XGA-based resolutions
|XGA||1024 x 768 pixels|
|WXGA||1152 x 768 pixels to 1366 x 768 pixels|
|XGA +||1152 x 900 and 1152 x 864 pixels|
|WXGA +||1440 x 900 pixels|
|SXGA||1280 x 1024 pixels|
|SXGA +||1400 x 1050 pixels|
|WSVGA +||1680 x 1050 pixels|
|UXGA||1600 x 1200 pixels|
|WUXGA||1920 x 1200 pixels|
|QWXGA||2048 x 1152 pixels|
|QXGA||2048 x 1536 pixels|
|WQXGA||2560 x 1600 pixels|
At this point it is worth mentioning that resolutions that have 720 lines or more can also be considered High Definition, such as QSXGA (2560 x 2048 pixels), WQSXGA (3200 x 2048) pixels; HUXGA: 6400 x 4800 pixels and WHUXGA: 7680 x 4800 pixels.
Faced with the advent of mobile devices with increasingly sophisticated and larger screens, the market ended up converging to a «standard» resolution with strong commercial appeal, HD (High Definition), which was «in the mouth of the people» because of the transition to high definition TVs. The Motorola Moto G can be cited as a representative of this category.
A screen with HD resolution is 1280 x 720 pixels, which in turn combines with screens widescreen (16: 9). In general, screens with this resolution have quite satisfactory image quality. You just need to be careful not to confuse it with its two variations: the nHD, which has 640 x 360 pixels and the qHD, which has 960 x 540 pixels.
720p is also used to indicate HD resolution. But, where did this letter come from «P«? Well, the content of a screen is updated several times per second, and the speed with which this occurs is called Refresh Rate or «Refresh Rate», which is measured in Hz (Hertz). A 60 Hz TV, for example, updates the image on the screen 60 times per second.
The detail is that in some resolutions the device may not be fast enough to update the entire screen at each cycle. Then a trick is used that takes advantage of the persistence of human vision: first only the even lines are updated, then the odd ones. As this is done quickly, our eyes do not perceive and see a single image.
When this trick is used the image is said to be interleaved, and we add a i to resolution, for example, 480i. But when all the lines on the screen are updated every cycle, we say that the image is in Progressive Scan, and we add the P the resolution. In other words, a 720p screen at 60 Hz means that all 720 lines are updated 60 times per second.
If HD already results in very good images, Full HD appears to offer an even more enriching experience. The term, which can also be abbreviated as FHD (although this acronym is rarely used), represents the resolution of 1920 x 1080 pixels, which is also appropriate for the 16: 9 aspect ratio. Like HD, Full HD gained strong commercial appeal, something like «HD is good, but Full HD is even better».
Full HD resolution is also known as 1080p. HD and Full HD resolutions have become a benchmark in the market, which is very useful because this aspect reflects the standardization of video and image formats, for example. As the following summary shows, the variations are few:
List of HD, Full HD and derived resolutions
|HD (720p)||1280 x 720 pixels|
|nHD||640 x 360 pixels (a quarter of HD)|
|qHD||960 x 540 pixels (a quarter of Full HD)|
|Full HD (1080p or FHD)||1920 x 1080 pixels|
|QHD or WQHD||2560 x 1440 pixels (also called 1440p)|
Since the minimum amount of pixels vertically for a resolution to be considered high definition is 720p, it was informally created that any value above that is HD.
HD + and Full HD + (FHD +)
With the appearance of 18: 9 or 21: 9 screens on smartphones, new resolutions have also emerged that better accommodate these proportions. We call HD + any resolution that is based on 720 lines, such as 1480 x 720 pixels. If the resolution is based on the 1080 lines of Full HD we call it FHD +, as 2220 x 1080 pixels. The exact number of columns will depend on the aspect ratio of the screen, and may vary slightly from manufacturer to manufacturer.
4K and UHD resolution
UHD (Ultra HD) is a term that describes any resolution above Full HD. An example is 4K resolution, which is common only on televisions 50 inches or larger. That’s because the human eye can hardly notice the difference between Full HD and 4K on small screens. So, while possible, smartphone manufacturers are unlikely to adopt 4K screens in the near future.
Main UHD resolutions
|2K||2960 x 1440 pixels|
|2K DCI||2048 × 1080 or 1998 x 1080 pixels (uncommon)|
|4K (UHDTV or QFHD)||3840 x 2160 pixels|
|4K (Ultra Wide HDTV)||5120 x 2160 pixels|
|4K DCI||4096 x 2160, 4096 x 1716 (uncommon) and 3996 x 2160 pixels (also uncommon)|
Remember that although they do not have a 4K screen, many smartphones are capable of recording 4K video. In this case, to see the image with all its details you will have to use a 4K TV, since on the smartphone screen the image will be reduced to the device’s native resolution.
What does the «K» mean in 4K?
Like HD and Full HD, the term 4K not only refers to a resolution but also has a strong commercial appeal. Even though you can identify this pattern as Ultra HD or UHD, 4K is the most used expression. This is because the letter «K», in English, is used to represent the number thousand and its multiples. So, if you have 2,000 or 3,000 units of anything, you can call that amount 2K or 3K.
As one of the UHD resolutions is 3840 x 2160 pixels, by approximation it became known as 4K.
What is your smartphone’s screen resolution? Are you satisfied with it?