On a typical 16:9 screen, 1080P is 1920x1080 progressive. My understanding is that it is the 1080 vertical lines that makes it look so clean. You could make a custom res with less horizontal lines, but as long as the vertical still has 1080 lines it still would look good.

I ask because I have a scaler (Centerstage cs2) which has some fixed res - one is 1080P - though it is 960x1080 (the horizontal lines are half of the 1920). I beliueve they did that because the cs2 is limited to a total clock spped of 135mzh, and a true 1920x1080@48 would be over the 135 limit (and many other popular 1080P settings would too) - so to get around this they made the horizontal half which allowed for a higher scan rate.

I also ask because I have a 4:3 screen vs the normal 16:9. If 1920x1080 is considered 1080P on a 16:9 screen, then what is 1080P on a 4:3 screen. If the 1080 vertical lines is what makes 1080P look good, then 1080P on a 4:3 is 1440x1080. Though if the 1920 horizontal lines is what makes 1080P look so good, then 1080P on a 4:3 screen is 1920x1440.

This is making me nuts - any advice would be appreciated.

Since the pixels are square, I don't think it makes any difference visually whether it's the H or V component that dominates. The total video bandwidth of 1080p is the product of H x V x 60 or 124 Megapixels per second. I'm not sure why your scaler halves the horizontal resultion to 960.

It used to be with CRTs that the horizontal and vertical retrace periods sucked up as much as half of the display time, increasing the required pixel clock. I'm not sure what dead times exist in matrix display technlogies like LCDs, since there is no electron beam that has to be steered around.

I believe its 1920 vertical lines (horizontal resolution) and 1080 horizontal lines (vertical resolution). Your scaler would be reducing the horizontal resolution down to 1440 vertical lines.

The use of the word "lines" causes a lot of confusion.
It is far better to think of a 1080P display as one that has 1080 rows each row of which contains 1920 square pixels.

The use of the word "lines" causes a lot of confusion.
It is far better to think of a 1080P display as one that has 1080 rows each row of which contains 1920 square pixels.

Exactly! Some people make it more complicated than it really is.

So, why has no one actually answered the question.

Yes, I know that 1080P is 1080 rows of 1920 square dots - that is because most people what hdtv on 16:9 (1.78 ratio) screens and 1920x1080 is a 1.78 ratio - also most hdtv content comes native in 1.78 (or higher such as 2.40). Anyway, if someone has a 4:3 screen (or 1.33 ratio), then what is 1080P on such a screen. Is it 1080 rows??? If 1080 rows is what defines 1080P, then on a 4:3 screen 1080p would be 1440x1080. Though if the 1920 squares across the rows is what defines 1080P, then on a 4:3 screen 1080P would be 1920x1440.

So, what is 1080P classified on a 4:3 screen. Basically, I still have a 4:3 120" screen, and will be converting (stretching, zooming, etc) all native 16:9 formats to git the 4:3 screen. I also have a scaler that allows me to create custom resolutions. I will be playing true 1080P movies (likely 1.78 or 2.4 ratio) and want little to no resolution loss. I do not mind the stretching, zooming, etc but want to truly be watching my 1080P movie in 1080P.

Thanks

To answer directly, 1080p reflects the number or display rows from top to bottom of the screen.

But when the aspect ratio of the screen doesn't match the aspect ratio of the source material, something's got to give. With your 4:3 screen, to display widescreen material in proper perspective, you've got to fit the full width of the image horizontally, necessarily leving blank space at top and bottom. Otherwise you either get distortion (tall skinny people), or horizontal clipping.

Personally it drives me crazy seeing distorted or clipped video.

720p or 1080p wide screen 16:9 aspect ratio programs can normally displayed on 4:3 aspect ratio screens in either letterbox format(no distortion) or in zoom format(cuts off the top and bottoms).
So you can not see all of a 1080p programs 2.1 megapixels on a 4.3 aspect ratio display unlesss the display itself has a native resolution higher then 1920x1080. Letterbox is probably your best bet. I am not aware of any standard options to stgretch letterbox format vertically to eliminate the black bars at the top and bottom.
Would a solution such as this be satisfactory if available?
What is the actual native resolution of your display (if digital) or the maximum scan rate(if CRT analog)?

Walford, I've got a NEC xg75 crt - all crt tubes are native 4:3 but many set them up on 16:9 screens. When they do this, they are using less of the tube, wearing it out faster, but also in my opinion not getting the biggest picture available. BTW - the NEC xg75 has a lot of capability - it can resolve 1080P and still look sharp depending on the scan rate (48hz looks good - higher is pushing it).

I guess I have a 4:3 screen because I wanted the BIGGEST picture available in my threare room. I was limited to about 8 (or so) feet wide, and then had a decision. Go 16:9 format and get only about 5' height, or go approx 7.5' height and go 4:3. Since height was not a limiting factor, and since about 50% of my sources are in 4:3 native format (ie. SD sat, cable, xbox1, xbox360) I went with 4:3. Though when I watch a true 1080P movie in original 16:9 aspect, I still want my entire screen showing an image and not have the bars on top or bottom. My scaler has options to "force" a 16:9 image fit the 4:3 screen, with either zoom, crop, or whatever it does - I really I will loose the right-most and left-most portions of the movie, but who cares - the eye watches the center of the movie where the picture/action is and the left-most and right-most are there just to fill in the gap.

So, what I'm strugglin with is if I have a true 16:9 1080P movie and will be forcing my scaler to fit it into a 4:3 screen, what custom resolution do I create on the scaler to get the full 1080P quality of the original. Do I create a 1440x1080 resolution or a 1920x1440 - both of these are 4:3 ratio resolutions. I know I can just stick with a true 1080P resolution on the scaler, though I'm trying to optimize "active image scaling".

Thanks

It asppears that when watching 4:3 Aspect ratio content that you should then be sending and displaying 480i.
And if watching 16:9 aspect ratio content that you want to use "Center Cut" zoom over 1080i since that will display on full screen the full pixel content of the meaningfull content of the program without distortion on your 4:3 aspect ratio display. You will notice that the the 16:9 aspect ration sources try hard to have no meaningfull content on the sides since they know that their programs will in many cases be centercut and downscaled to 480i or 480p.

The digital to analog converter coupon supported by the government arel required to have the center cut option for just this reason.

Walford, I've got a NEC xg75 crt

Hi there

I also have a NEC CRT PJ, although it's just a 6100, and can relate to the desire to project the biggest/brightest image possible. Sort of like an IMAX at home.

For widescreen HD television programs, I usually crop the sides, since there is rarely any activity off to the sides. Maybe in the past month, there was only one drama where an actor got partially cropped out because he was not in the "safe zone".

But for a movie, I prefer to view in the aspect ratio that the director intended.

Do I create a 1440x1080 resolution or a 1920x1440 -
I would recommend the 1440 x 1080 resolution. This represents a cropped image without any scaling.

The 1920x1440 resolution is bogus, because you're starting with a widescreen image that has a 16:9 aspect ratio and the only way to preserve the horizontal resolution when displaying that image at 4:3 would be if you stretch the image vertically or you letterbox it. You want to crop the sides of the image, and not rescale it at all.

Regards

ps Actually you need the 1920x1440 resolution for viewing 1080p content with letterbox. So one of the 64(?) memory banks should be for this setup.

It asppears that when watching 4:3 Aspect ratio content that you should then be sending and displaying 480i.

Hi there

Poor advice. Since his PJ is electrically/optically setup for 1080 horizontal scan lines, 480i would look horrible with very obvious scan lines. Sending 480i video to a data-grade PJ is a waste of such a projector.

I use an HTPC to drive the CRT PJ, and let the PC deinterlace and upscale the SD content to 960p. If the 4:3 content is low noise, the results can be very good, and can rival some of the (over-compressed) HDTV content.

Regards

Horizontal resolution is the key to better image quality.

Loss in vertical resolution is not going to result in the same loss in image quality as loss in horizontal resolution. If you had a source and display that could do a full 1920 horizontal, 540 vertical wouldn't be that much of a problem. On the other hand, if your source and display were doing 960 horizontal and 1080 vertical, it would look dull and lifeless.

Guys, thanks for the info so far. I'm starting to get a better understanding of what I'll need out of my scaler.

Ken, thanks for that explanation about horizontal being of grewater importance. I really thought it was the other way around. I though that the vertical scan lines in a typical 480i is what makes it ugly which is why adding vertical lines (ie. 1080 progressive) makes a movie look so much better. But based on your explaantion, it sounds like the vertical only impact the scan lines but the horizontal is what really makes a movei look sharp and life-like. Though based on your example, would 1920x540 not have major visble scan lines, vs a 1440x1080 which would have little to no scan lines (but apparently better sharpness)?

Thanks

I am not aware of any justification for Ken's description since the same number of square pixels are being displayed. if there is one I would like to have a link to it.
Dna,
What you need to do is use "Center Cut" cropping to display the center 1440x1080 pixels on your 4:3 display from your 1920x1080 program source to get true 1:1 square pixel mapping of the meaningfull content of the programs.

Think that Ken H is probably referring to the fact that many people haven't noticed 1080i content being displayed as 540p when cheap de-interlacing techniques are being used... (Though AIUI this is usually on 720/768 line panels rather than 1080 line panels)

I've had direct first hand experience, experimenting with different source and display resolutions in advanced visualization systems. This conclusion was born out in lab testing by a major industrial manufacturer.

Ken,
Interesting. Is there any engineering information as to why the lab testing results are what they were? Do you have a link to the lab report?
I ask since I am retired engineer and first worked with digital display systems for the Military over 35 years ago.

Do you have a link to the lab report?It was never released to the public.

Horizontal resolution is the key to better image quality.

Loss in vertical resolution is not going to result in the same loss in image quality as loss in horizontal resolution. If you had a source and display that could do a full 1920 horizontal, 540 vertical wouldn't be that much of a problem. On the other hand, if your source and display were doing 960 horizontal and 1080 vertical, it would look dull and lifeless.

Hi there

I suspect this generalization applies more to widescreen formats such as 16:9 than square-ish aspect ratios. From that example, the comparison is between 50% less horizontal lines versus 50% less vertical lines, but there are 77% more lines tossed in the horizontal resolution than the vertical.

OTOH I recall something about the human eye being more sensitive to horizontal motion than vertical motion. Perhaps this contributes to this resolution effect.

Actually, I think that answering the OP's question (in the title) will not lead to a suitable resolution for his CRT PJ. Instead of asking the simple/practical question of what resolution to use, he has posed a rhetorical question. His question does not account for scaling artifacts if he tries to use 1920x1440 with a full 4:3 image.

Regards

Hi there

I suspect this generalization applies more to widescreen formats such as 16:9 than square-ish aspect ratios.No, the original resolutions used as starting points for the testing were 1024x768 & 1280x1024.

Actually, I think that answering the OP's question (in the title) will not lead to a suitable resolution for his CRT PJ. Instead of asking the simple/practical question of what resolution to use, he has posed a rhetorical question. His question does not account for scaling artifacts if he tries to use 1920x1440 with a full 4:3 image.Agree. He should use 16:9 image size on the 4:3 screen.

I just realized that the OPs TV is a CRT model with I believe 8" guns. I assume that the TV is capable of scanning at 1080i which means that It may be able to actually display 16-1700 x 850-950 after allowing for gun size and line overlap.
Previously I had been assuming that the TV was a 1440x1080 digitla technology unit and not a CRT technology unit and my posts were based on that assumption.
I now understand why Ken's data is probably correct.

I note from the following link that the NEC XG75 CRT projector:

http://findarticles.com/p/articles/mi_m0EIN/is_1996_July_10/ai_18489871

has a maximum resolution of 1024x768.
The Projector appears to be designed as a PC monitor proector and has a maximum progressive resolution of 1024x768.

Therfore SD 480i video would probably be best displayed at 640x480 or 800x600.
1080i/1080p and 720p HD programs filmed with SD cameras as evidenced by the presence of side pilers would best be center cut and displayed at 1024x768.
1080i/1080p and 720p HD programs filmed with HD cameras could either be center cut at 1024x768 or be converted to a 576x768 letterbox.

I note from the following link that the NEC XG75 CRT projector:

has a maximum resolution of 1024x768.
The Projector appears to be designed as a PC monitor proector and has a maximum progressive resolution of 1024x768.

Hi there

Curt Palme's site is far more informative than a marketing blurb.

http://www.curtpalme.com/PJSpecs_NEC.shtm

http://www.curtpalme.com/Projector_Rankings.shtm

Therfore SD 480i video would probably be best displayed at 640x480 or 800x600.


You're writing poor advice again.

Regards

Thank you for the link it appears that the ones I found are all wrong.
I have to admit I am still confused as to what scan rates the OPs TV supports and what is the maximum resolution it can display as compared to the max resoloution it can accept over DVI.
A link to the units actual user manual would help to clarify the information since the following link from the link you provided is still somewhat confusing.

Hi there

The OP does not have a "TV". It's a commercial not consumer, data-grade CRT projector, sold by the industrial products division.
It has BNC composite video and RGBHV inputs. There is no DVI, since this PJ was manufactured before the specs were ever formulated. (If you wanted high-definition video in the 90s, data-grade CRT PJs and pro monitors were the only game in town. There was no need to wait for plasma or consumer TVs to offer HD.)

Actually the OP should have posted in the CRT projector forum, where other XG owners could offer specific advice.
Oops, the OP did that already.

Regards

Blue_z,
I agree with what you say I used the Term TV since that is how the OP is trying to use it as one by asking about the use of ATSC TV resoloutions with it.
Hopdfully he is getting responses to what his optios are in the CRT projector forum then we gave him here.

Guys, thanks for the replies - I have learned alot and getting closer to optimize my setup.

Yes, it is a commercial CRT projector. Yes, it does not have DVI, however I have a HDFury (google it) which converts DVI (any resolution input, undistorted) to VGA, and then I feed the projector via 5bnc breakout cable (rgbhv). The specs on the CRT are objective, though many on the CRT forum state that they run 1080P with these NEC XG units with extreme good results - many also like 1080i and few say 720P is the spot.

My specific question really is not CRT specific; if anything it is scaler specific or just HDTV specific. Basically, my CRT shoots onto a 120" 4x3 screen, and being that I also have a high end external scaler, I have the ability to scale any resolution to my screen. I read an article (see link below) stating that to optimize an image, you want to use "active image scaling" meaning that if you have a 16:9 screen and watching a true 1.78 aspect ratio, then you want a resolution output of 1920x1080 to get 1:1 mapping. Howver if you have a 16:9 screen and watching a native 2.35 or 2.4 movie, then if you use a 1920x1080 res, you are wasting bandwidth since the top and bottom are black bars but still part of the res - for a 2.4 movie, you want 1920x800 which lowers the bandwidth and thus allows for a higher scan (ie72mzh or even 96 or even 120). Since most HD movie are actual 2.4 aspect ratio, but my screen is 1.78 ratio (4:3), I am simply trying to determine what my custom res needs to be to get the full HD quality out of a 1080P movie.

So, this really is not a CRT specific question. I'm simply trying to confirm is 1920x1440 is the 1080P equivalent on a 4:3 screen, or 1440x1080. Based on the replies, it sounds like I want 1920x1080 and crop/chop off the sides, which really is 1440x1080 since when I chop off the left/right black bars, I will be watching 1440 horizontal lines by 1080 vertical. Thus I think my custom res is 1440x1080 which will allow me higher scan rates.

Thanks

Given that the source image is 1080p (ignoring any hard coded letterbox bars in the 1080p frame) then the source resolution is 1920x1080.

At a consumer/HTPC price point, scaling is one of the quickest ways to damage a picture, so anything you can do to avoid it is worthwhile. (Consumer scaling algorithms are often pretty crude)

As the 1920x1080 image is 16:9, and you wish to display it in a 4:3 frame, then - assuming everything else is equal - surely there is no question that you need to display the 1920x1080 source image as a 16:9 letterbox in a 1920x1440 4:3 frame?

That way the original image is displayed unscaled and unprocessed, with all the source pixels/samples displayed without any horizontal or vertical scaling and filtering (aka resampling), and the extra 180 lines top and bottom simply padding out the 16:9 frame to 4:3?

If you do anything else, you will be scaling/filtering/resampling horizontally and/or vertically, and this kind of processing will do nothing to improve picture quality, and is likely to reduce it.

HOWEVER - not everything in life is equal - and at higher resolutions you may find that the limitations of the display processing offset the lack of quality loss achieved by not scaling. (i.e. running at a lower resolution with extra scaling artefacts, may still be a better bet)

AFAIK the maximum resoloution that the OPs projector is either 1024x768 or 1600x1200 so it can not accept a 1920x1440 frame so the letterbox image itself wil have to be scaled.
Also since many programs especially daytime programs are using 4:3 aspect ratio SD cameras a 16:9 aspect ratio letter box is not a good solution for these progams when upscaled to 1080i since they you would have borders all around the actual program image. Therfore also being able to centercut to a 1440x1080 frame would be desirable.

The projector is a multiscan display. No scaling is necessary, or in this case desired; it would only degrade the image. Run the signal into the display using component video (may need a component video to RGBHV transcoder) and use H & V sizing to get the right aspect ratio. Very simple.

AFAIK the maximum resoloution that the OPs projector is either 1024x768 or 1600x1200 so it can not accept a 1920x1440 frame so the letterbox image itself wil have to be scaled.
Also since many programs especially daytime programs are using 4:3 aspect ratio SD cameras a 16:9 aspect ratio letter box is not a good solution for these progams when upscaled to 1080i since they you would have borders all around the actual program image. Therfore also being able to centercut to a 1440x1080 frame would be desirable.

But isn't scaling a 4:3 centre cut SD pillarbox - which is probably derived from a 720x480 source (or an NTSC composite source) - from 1440x1080 to 1920x1440 - less worse than scaling a 1080i source?

I was under the impression that the display was a CRT model so had no native resolution? (If spot size can be adjusted)

I had also assumed that as the projector was a data model - a scaler or HTPC would be used to do the scaling?

If the CRT scans can be adjusted so that it scans a 1920x1080 16:9 window natively (and effectively letterboxes by analogue scanning) - then that may also work nicely, though will leave you with a pillarbox rather than full-frame 4:3 image when fed SD pillarboxed to HD (as the display would then be running in 16:9 native mode, and leaving a portion of the 8" guns unused?)?

SD Pilerbox is derived from NTSC source upscaled for broadcast in either 1080i or 720p CBS, NBC amd ,most of the PBS stations use 1080i; ABC, FOX and ESPH HD use 720p.
One of the problem with the appearance of letterbox SD pilerbox is that the networks do not all use black piler bars some use blue or gray instead.
The networks when using 1080p cameras all make sure there is no manaingful content on the sides since they then use centercut theselves and downscale the content to support 4:3 NTSC analog cable, broadcasts, and TVs. There is very obvious when watching spporting events where score data is displayed or when watching the weather data from TV stations using all 16:9 cameras in their studios.
Yes, the CRT projector is a multiscan PC monitor, but it has a maximum resolution of 1600x1200 which makes sense for a projector with 8" guns since the phospher dot density probably would not support anything higher.

Yes, the CRT projector is a multiscan PC monitor, but it has a maximum resolution of 1600x1200 which makes sense for a projector with 8" guns since the phospher dot density probably would not support anything higher.

Don't multiple CRT projectors have no issue with phosphor dot density - as each gun is uniformly covered in phosphor, with no shadow-mask/PIL tube issues and no resulting dots? This also allows them to be MUCH brighter, as they don't have issues with heat deforming the shadow mask etc.

My understanding was that 3 tube CRT displays were resolution limited by other issues - spot size, bandwith of video processing, performance of line/field scan circuits etc.

Good input. I am afaid I was confusing spot size with phospher dot density.

Don't multi-gun CRTs have no issue with phosphor dot density - as each gun is uniformly covered in phosphor, with no shadow-mask/PIL tube issues and no resulting dots?

You're misusing the term "gun" with CRT.
Actually "multi-gun CRT" is what is used in a direct-view display; three electron guns in one CRTube firing at a screen with 3 phosphors.
A 3-CRTube projector uses three single-gun CRTs.

My understanding was that 3 tube CRT displays were resolution limited by other issues - spot size, bandwith of video processing, performance of line/field scan circuits etc.

True. There are many individual bandwidth limitations within the projector.

Regards

You're misusing the term "gun" with CRT.
Actually "multi-gun CRT" is what is used in a direct-view display; three electron guns in one CRTube firing at a screen with 3 phosphors.
A 3-CRTube projector uses three single-gun CRTs.


Doh - should read before I hit post. I didn't mean to type multi-gun - am well aware of the difference between an electron gun and a CRT!