Aspect Ratio
Posted: Mon Nov 05, 2018 1:29 pm
I am reprinting several earlier articles from the old forum in this thread in the new forum.
One aspect of the HDS Gen2 Touch that was somewhat troublesome for me was the screen dimension. And here I am using aspect as an intentional double entendre. The HDS Gen2 Touch screen has a much different aspect ratio than the HDS units that preceded it.
My HDS-8 has a screen with pixel dimension of 800 x 600, which is the classic 4:3 ratio. Display screens with a 4:3 ratio were the most common for decades. The 4:3 ratio was a product of the NTSC television standard. Television display devices needed to display an image from television video that was transmitted in a 4:3 format. The display industry made 4:3 displays in huge volume to provide television manufacturers with suitable displays.
It is also interesting to note that the typical field of vision of the human eye is also in nearly an identical 4:3 aspect ratio. One source says human vision is nominally 155-degrees horizontally by 120-degrees vertically, for an aspect ratio of 4:3.075
But NTSC television is now a relic of a previous age, and the new standard for television is High-Definition TV or HDTV in the USA. HDTV typically is a widescreen format, with the aspect ratio of 16:9 being the most common. The HDS-9 Gen2 Touch has a screen with pixel dimensions of 800 x 480. This is an aspect ratio of 1.66:1 or 5:3 or 15:9. It is not quite as wide as a HDTV widescreen display, but almost. It seems there was an earlier Japanese standard that used 5:3 aspect. Perhaps this might be related to the display used in the HDS-9
You don't have to be a math savant to figure out that the new model has a screen with fewer pixels than the old model.
HDS-8
800 x 600 = 480,000-pixels on screen
HDS-9
800 x 480 = 384,000-pixels on screen
There are 96,000 fewer pixels on the HDS-9 than on the HDS-8. That is a loss of 20-percent of the screen. It seems entirely reasonable to say that the HDS-9 has a screen that is 20-percent smaller than the HDS-8. If the model numbers were going to be assigned so they were proportional to the number of pixels on the screen, we should call the HDS-9 the HDS-6.4 instead.
Now with some more math, we can figure out additional comparisons. If we know the diagonal length and the aspect ratio, we can compute the height, length, and area of the screen. Let me do this for the HDS-8 and the HDS-9
HDS-8
Diagonal width = 8.4-inches
Aspect ratio = 4:3 or 1.333
Height = 5.05-inches
Length = 6.71-inches
Area = 33.9-square-inches
HDS-9
Diagonal width = 9-inches
Aspect ratio = 5:3 or 1.66
Height = 4.64-inches
Length = 7.71-inches
Area = 35.8-square-inches
In this comparison the HDS-9 looks better. The screen area is actually larger than the HDS-8 by about one-square-inch. Again, if the model numbers were going to reflect the screen area, then the HDS-9 would be called the HDS-8.4.
However, the HDS-9 has fewer pixels and they must cover a larger area, so the pixel resolution is somewhat coarser. Again let's compare:
HDS-8
Pixels = 480,000
Area = 33.9-square-inches
Pixels-per-square-inch = 14,159-pixels-per-square-inch
HDS-9
Pixels = 384,000
Area = 35.8-square-inches
Pixels-per-square-inch = 10,726-pixels-per-square-inch
In this comparison we could say the HDS-8 has about a 32-percent improvement in resolution compared to the HDS-9
The matter of the screen aspect ratio is made confusing in part by Lowrance. In the Lowrance literature they describe the HDS-9 as having a "widescreen, 16x9 display." Clearly a display with a 16x9 aspect ratio is one with a 1.77:1 aspect ratio. However the pixels on the screen are in the ratio of 800:480, which is a 1.66:1 ratio.
Compare at: http://www.lowrance.com/en-US/Products/ ... rtplotter/ HDS9-Gen2-Touch-en-us.aspx
Perhaps the pixels used by Lowrance are not square pixels. If that is the case, we might have to recompute the screen area based in the display actually being a 16:9 display. This would then give the following result:
HDS-9
Diagonal width = 9-inches
Aspect ratio = 16:9 or 1.77
Height = 4.42-inches
Length = 7.84-inches
Area = 34.7-square-inches
Now we see that the screen area of the HDS-9 is less than we thought, and the improvement over the HDS-8 is only by 0.8-square-inch. The other comments about the number of pixels are not affected because the number of pixels is the same in either case, but the actual screen area is different, making a difference in the density of the pixels, which is now 11,066-pixels-per-square-inch, a slight improvement over the first calculation (which assumed a 5:3 aspect ratio).
--
If you want to check my math, see http://en.wikipedia.org/wiki/Aspect_ratio_(image) for the formulas.
One aspect of the HDS Gen2 Touch that was somewhat troublesome for me was the screen dimension. And here I am using aspect as an intentional double entendre. The HDS Gen2 Touch screen has a much different aspect ratio than the HDS units that preceded it.
My HDS-8 has a screen with pixel dimension of 800 x 600, which is the classic 4:3 ratio. Display screens with a 4:3 ratio were the most common for decades. The 4:3 ratio was a product of the NTSC television standard. Television display devices needed to display an image from television video that was transmitted in a 4:3 format. The display industry made 4:3 displays in huge volume to provide television manufacturers with suitable displays.
It is also interesting to note that the typical field of vision of the human eye is also in nearly an identical 4:3 aspect ratio. One source says human vision is nominally 155-degrees horizontally by 120-degrees vertically, for an aspect ratio of 4:3.075
But NTSC television is now a relic of a previous age, and the new standard for television is High-Definition TV or HDTV in the USA. HDTV typically is a widescreen format, with the aspect ratio of 16:9 being the most common. The HDS-9 Gen2 Touch has a screen with pixel dimensions of 800 x 480. This is an aspect ratio of 1.66:1 or 5:3 or 15:9. It is not quite as wide as a HDTV widescreen display, but almost. It seems there was an earlier Japanese standard that used 5:3 aspect. Perhaps this might be related to the display used in the HDS-9
You don't have to be a math savant to figure out that the new model has a screen with fewer pixels than the old model.
HDS-8
800 x 600 = 480,000-pixels on screen
HDS-9
800 x 480 = 384,000-pixels on screen
There are 96,000 fewer pixels on the HDS-9 than on the HDS-8. That is a loss of 20-percent of the screen. It seems entirely reasonable to say that the HDS-9 has a screen that is 20-percent smaller than the HDS-8. If the model numbers were going to be assigned so they were proportional to the number of pixels on the screen, we should call the HDS-9 the HDS-6.4 instead.
Now with some more math, we can figure out additional comparisons. If we know the diagonal length and the aspect ratio, we can compute the height, length, and area of the screen. Let me do this for the HDS-8 and the HDS-9
HDS-8
Diagonal width = 8.4-inches
Aspect ratio = 4:3 or 1.333
Height = 5.05-inches
Length = 6.71-inches
Area = 33.9-square-inches
HDS-9
Diagonal width = 9-inches
Aspect ratio = 5:3 or 1.66
Height = 4.64-inches
Length = 7.71-inches
Area = 35.8-square-inches
In this comparison the HDS-9 looks better. The screen area is actually larger than the HDS-8 by about one-square-inch. Again, if the model numbers were going to reflect the screen area, then the HDS-9 would be called the HDS-8.4.
However, the HDS-9 has fewer pixels and they must cover a larger area, so the pixel resolution is somewhat coarser. Again let's compare:
HDS-8
Pixels = 480,000
Area = 33.9-square-inches
Pixels-per-square-inch = 14,159-pixels-per-square-inch
HDS-9
Pixels = 384,000
Area = 35.8-square-inches
Pixels-per-square-inch = 10,726-pixels-per-square-inch
In this comparison we could say the HDS-8 has about a 32-percent improvement in resolution compared to the HDS-9
The matter of the screen aspect ratio is made confusing in part by Lowrance. In the Lowrance literature they describe the HDS-9 as having a "widescreen, 16x9 display." Clearly a display with a 16x9 aspect ratio is one with a 1.77:1 aspect ratio. However the pixels on the screen are in the ratio of 800:480, which is a 1.66:1 ratio.
Compare at: http://www.lowrance.com/en-US/Products/ ... rtplotter/ HDS9-Gen2-Touch-en-us.aspx
Perhaps the pixels used by Lowrance are not square pixels. If that is the case, we might have to recompute the screen area based in the display actually being a 16:9 display. This would then give the following result:
HDS-9
Diagonal width = 9-inches
Aspect ratio = 16:9 or 1.77
Height = 4.42-inches
Length = 7.84-inches
Area = 34.7-square-inches
Now we see that the screen area of the HDS-9 is less than we thought, and the improvement over the HDS-8 is only by 0.8-square-inch. The other comments about the number of pixels are not affected because the number of pixels is the same in either case, but the actual screen area is different, making a difference in the density of the pixels, which is now 11,066-pixels-per-square-inch, a slight improvement over the first calculation (which assumed a 5:3 aspect ratio).
--
If you want to check my math, see http://en.wikipedia.org/wiki/Aspect_ratio_(image) for the formulas.