#photo-cd 2 PAR. What rez
16 messages in this thread
I'd like to transfer some photo-cd images of my recent holidays to my PAR and
save them as stills. What kind of cropping or scaling would I need to do to the
original image? The closest resolution is 768x512x1.0 aspect. The PAR is
752x480x0.85 aspect. I'm thinking I should end up with some type of letterbox
image to preserve the physical aspect of the original image (3:2 or 1.5:1)
whereas the TV is 4:3 or 1.33:1.
Martin:
To keep your images from squishing horizontally I think you'll need to stretch
them in the x direction by 17.5%. I'm sure there is going to be a debate about
this but here's what I'm figuring:
You gotta crop your image down or scale it down so that the x is less than or
equal to 640 pixels and the y is less or equal to 480 pixels. This is a given
or you'll lose some part of the image. When I do this I scale the image down
in Pstyler to maintain its same proportions.
Next, scale the image in the x direction back up so that you go from 640 pixels
across to 752 pixels. My reasoning is that 752/640 = .85 which is the aspect
ration of the PAR.
If your dimensions are less than 752 x 480 for your final .tga then you'll get
a centered image with black fill so, yep, you'll get a letterbox.
Bob
PS. I gripped your book today, I'd swear that photo of you was taken at
SIGGRAPH.
Bob,
>> Next, scale the image in the x direction back up so that you go from 640
pixels across to 752 pixels. My reasoning is that 752/640 = .85 which is the
aspect ration of the PAR. <<
Interesting theory – sounds like you'd be scaling twice. My theory was to scale
the from 768×512 to 752×408. My reasoning was that 480 x .85 is 408. The
results look OK but I'm looking for more opinions from the brainboxes in the
forum 🙂
Martin,
The aspect ratio of .85 Horiz. is used to create a 1:1 image on the PAR from a
640 x 480. We are using a 752 x 480 image to create the final output to the
PAR, you arrive at this by multiplying 640 x 1.175 = 752. If you multiply 768 x
1.175 = 902 which gives an image of 902 x 512 for the proper aspect for the PAR
(much to BIG). So bring the 902 down to the 752 PAR resolution and this will
fit onto the Horiz. and leaves you with 426 for the Vert. and 27 lines top and
bottom of black to create your letterbox.
902 512
— x — = 426.9
752 Y
Hope all these numbers makes some sense to you this late in the Evening!
Mike Morgan, CAD Forms Inc.
Mike,
>>
902 512
— x — = 426.9
752 Y
<<
sounds good to me. I was thinking 408, but your formula looks much better than
mine 🙂
Martin:
You could definitely do the operation in one pass and with PhotoStyler its easy
enough to play with the numbers in resample as it will give you the calculation
results before you do the scaling. However, for all 768 x 512 images I would
use 752 x 427 as the final image size but I'll be content to listen to the
'brainboxes'.
Bob
Bob,
>> I would use 752 x 427 as the final image size <<
I'll try that. Sounds good.
Bob,
>> PS. I gripped your book today, I'd swear that photo of you was taken at
SIGGRAPH. <<
I had to respond to this <g>. That photo was actually taken in Melbourne,
Australia (home of the famous Glenn Melenhorst [major character mutant]). I
used the self-timer on me Minolta 🙂 Also, I've lost 30lbs since that photo – I
was a real fat bastard then <G>.
Martin:
/_____________From your message_____________\\
I was a real fat bastard then <G>.
_______________________________________________
Now you opened up a can of worms. You gotta have the explanation for this 'fat
bastard' phrase as I've encountered it in British rock and roll several times.
For instance, I'm at a dive club in a nasty section of Trenton, N.J.
anticipating the British Ska band 'Bad Manners' to come on stage. To get the
lead singer (300 lb + bald headed Buster Bloodvessel) to come out and join the
band I found myself cheering with everyone "YOU FAT BASTARD". Why was I doing
this? Another example is on the CD '30 Something' by 'Carter The Unstoppable
Sex Machine'. In the first song "Surfin' USM" the spoken intro is something
like, "When you're younger you can eat what you want, you can drink what you
want and still climb into your 26 inch waist trousers and zip them closed.
Then you reach that age, 24 25, your muscles give up, they wave the little
white flag and without any warning at all you're suddenly a fat bastard." Then
the tune kicks in with a crowd chanting, "YOU FAT BASTARD!!" What's the story
behind this phrase?
Bob
PS. I thought the photo was kinda cool. The strap across your shoulder is
left up to the viewers imagination. Does he have a camera? a satchel? perhaps
a laptop? One has to fill in the blank.
Martin and Robert:
>>752/640 = .85
????
I'm no brainbox as Martin puts it but last I checked 752/640 = 1.175 not .85.
<BG>
The easy way I do this is to port the graphic into 3DS as a background and
rerender at the proper pixel AR using the background/ rescale feature in the
renderer. 3DS always seemed to do a better job than photoshop for rescaling
and it doesn't require math to figure it out. Its fast and you can output with
the PXP directly to the PAR as the still. That YOST "brainbox" takes care of
all the math for you and you just have one button to click on. And, as you
already discovered you will still get a letterbox because, ultimately you will
need to end up with .75 AR for video. The problem is you have 768×512, a tall
format you want to scale to completely fit on the landscape NTSC monitor
format. Since this is a tall vertical format picture you will need to adjust
the vertical to fit in the monitor screen allowing the sides to letterbox.
512/768 = .666 AR which is, by the way, the AR for 35 mm slide and print film.
I assume you shot the pictures with a 35mm camera. (Just call me Sherlock, Dr.
Watson!). Even with a landscape format shooting style you will still get the
letterbox because of the wider 1.5 AR of 35mm film.
FYI: I get many requests for putting slides to video here and on my instr
sheet I explain the the best way to shoot the 35mm camera for output to video
is to ALWAYS use horizontal format, and, frame your subject to leave an
imaginary border on each side of about 10%. If my customers follow these
instructions I can put their slides to video, full screen, without
letterboxing. Even shooting slides for a slide show I never shoot vertical
format. The only time I ever shoot vertical is with print film. I could just
cringe when I see a slide show and the format switches from horizontal to
vertical mid show. Usually the tops and bottoms are off the screen. Oh there
I go again on one of my pet peeves.
Don,
>> 3DS always seemed to do a better job than photoshop for rescaling and it
doesn't require math to figure it out. <<
I don't think it's that simple. 3ds isn't going to do the math for you. For
example, how would 3ds come up with 752×426?
Also, I want to convert my vertical format photos (portrait format) to the PAR.
With a bit of math I came up with 376 x 480. I don't think 3ds would have
calculated this for me. Or would it?
I don't think you see what I'm doing here, Martin. When you specify the
rescale background and specify the PAR res requirement the PAR will
automatically calculate all this and center the picture. Just put your slide
rule away and try it. It works for me and whatever format, portrait or
landscape, the 35mm scans always come in centered with the appropriate letter
box borders. It's when you want to make the picture full screen that it gets
complicated. But you're right about one thing, there are no calculations in
3DS that you see, just the proper PAR output.
Don,
>> I don't think you see what I'm doing here, Martin. When you specify the
rescale background and specify the PAR res requirement the PAR will
automatically calculate all this and center the picture. <<
you are right, I don't see what you are doing and I think I already tried it
and it didn't provide the right physical aspect. You are being very vague – I
need specifics and then I'll try it <g>. OK, let's assume I'm completely dumb
and you are going to need to spell this out for me.
1) in 3ds keyframer set up the background as a sequence of photo-cd images
which will be 768×512 and have not yet been scaled.
2) turn on Rescale Background.
3) render to my par-drive, but with what numbers in the width, height and
aspect ratio boxes? 0 x 0 x 0? Or 752 x 480 x 0.85?
If you answer these questions I'll try it again.
Martin
>>Or 752 x 480 x 0.85?
YES!
Last time I did some of these slides was about a month ago and it worked great.
Just be sure you select rescale, not tile. I'm doing some rendering to the PAR
for the next 24 or so hours but when its done I'll check it out again and try
to figure out why you're having trouble with this. There must be something I'm
leaving out of the process I take for granted but right now I can't figure what
it is. I just know that when I did this it was simple and didn't give it much
thought.
Martin:
>> I'd like to transfer some photo-cd images of my recent holidays to my PAR
>> and save them as stills.
Just to throw another idea at you, have you considered just bringing them in
through a video camera plugged directly to the TBC-IV? Works great, no aspect
problems, and a lot faster than a scanner! Just a thought…
Greg Pyros
Greg,
>> have you considered just bringing them in through a video camera plugged
directly to the TBC-IV? <<
no, I haven't actually. Mainly because I don't have a video camera, I'm ashamed
to say 🙁
I now have a fairly automated way of achieving this, though. As you may know,
the latest version of image alchemy (1.77) has photo-cd conversion built in –
very cool. This means I can do a batch file conversion of images to PAR in one
operation (hooray!). The upgrade from 1.6 was $20 – and worth it at twice the
price, I'd say 🙂
FWIW, I decided on 752×427 for the landscape shots and 372×480 for the portrait
shots and this seems to be about right mathematically and visually.