Another newbie question about stills

[Mike Kujbida]

dpi is a photographic term and is not relevant to video.
The only thing that matters in video is the image size in pixels.
The general “rule of thumb” for stills in video is to not exceed 2X your project properties.
This maintains quality and still allows you to do some mild zooming in on the image.
For NTSC DV, this would be a maximum of 1440 x 960.
For HD 1080 (your size), this would be 3840 x 2160.
Keep in mind that this is a fairly large image and too many of them on your timeline may lead to render issues.
The only time you would break this “rule” is if you’re doing some deep zooms.

[Adrian Perez]

Mike,

First thank you so much for replying to my question. As I was about to head off to bed I thought I’d check and see if anyone had replied and there was your response.

Maybe I’m thinking of this too “photo-centric”, as I’m not understanding how to go about this. For example in Photoshop I took the same photograph and assigned it the pixel size you mentioned (3840 x 2160) in both 72 & 150 dpi. As you can see in the attached image, I had two entirely different results size-wise, but both were at the overall pixel size you suggested. Am I just not getting it? I keep getting stuck on how much detail I might or might not get depending on the dpi I import the stills in.

Thanks again for the reply, and if I don’t reply back this evening it’s only due to my long work day. 🙂

[John Rofrano]

The key here is “Document Size”. In video there is no “document”. What that screen is telling you is that if you were to print that image at 72 dots per inch it would be 53 inches across, but if instead, you packed 150 dots per inch, it would only be 25 inches wide. Smaller dot… smaller printed picture. The “image” has exactly the same quality (amount of information) in both cases. It is just being printed with smaller or larger dots.

The “dot” on your computer monitor can’t get smaller. You can’t pack more to the inch. So DPI has no effect. If you want a comparative size, your normal computer monitor is 96 DPI. So setting the DPI to 96 will give you “information” about how big the image might appear on your display. Of course, it will really depend on how many “pixels” per inch your computer monitor actually has which is dependent on the physical size of the monitor.

Note in both cases the Pixel Dimensions did not change. Since your computer monitor is based on pixels, the picture quality did not change regardless of the DPI setting (which is primarily a “printer” setting)

Does that make sense? (if not, ask more questions)

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Adrian Perez]

Ah! I think I’m finally getting it. The reason I’m fixated on this is that I am trying to use a lot of older digital photos that are at are at 1600×1200 resolution (72 dpi, but that doesn’t matter). If I go by Mike’s earlier suggestion I would need to boost the width and height by over 200% (enlarging them to 3840×2160), which I’m afraid would produce very pixelated images when projected. Again, I’m coming at it from a different angle (more print I guess) so if I seem particularly dense about this…well, you and my girlfriend can have a good laugh over coffee! But I’d really love to use these photos yet everything in me is saying that I can’t “boost” the images by that much without serious image distortion. Does that make sense?

Also, since I have your ear (eyes): I would like to produce this in HD and thought (as most newbies do I’m sure), “Why I’ll just make it at the highest possible resolution (1920×1080) so it’ll look the absolute best it can!” But now I wonder if I shouldn’t aim for the 720 version of HD (1280×720) instead. My eventual goal with this project is festivals, etc. But I’m stumbling at the moment because I studied film – actual film – back in the 90’s but this is all new to me. Would you recommend one over the other?

Thanks again. This whole forum has been like going back to school for me.

[John Rofrano]

The recommendation of using double resolution is really to reduce the size of 8 – 10 mega pixel images down to something reasonable that will still allow you to zoom in a bit if you need to. If your images are already smaller that 1x your resolution then do not enlarge them past 1x.

The decision to go with 720p is up to you. If you crop 1600×1200 pictures to 16:9 you’ll have 1600×900 which means you would have to enlarge them by 180 vertical pixels to reach 1920×1080. That still might not look too bad but I would definitely not try and zoom in too much on any of them. Since the images are progressive media, 720p might not be a bad way to go. Do some test renders and decide for yourself which looks better to you.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Adrian Perez]

Thanks John. I think the light has now reached me. I do have one last question that would help settle me:

Since I plan on doing no panning/scanning/zooming with my photos, is it okay in your opinion to keep the resolution at a 1:1 ratio? For example it was suggested that I use double the resolution of whatever video resolution I was going for. So if I am going with 1920×1080 resolution it was suggested my photos should be at 3840×2160, which makes sense to me if I was planning on zooming, etc. But since I won’t be can I keep the photos at 1920×1080 (or 1280×720 if I’m going 720p) without worry?

I ask because if that is what I can do, then I might go with the 720p just to be able to use some photos I would love to but might not look so good in 1920×1080.

Again, thanks to you (and Mike) for your time.

Adrian

[Mike Kujbida]

Adrian, since you don’t plan to do any zooming in, there won’t be any issue in using these images in Vegas.
You said that you originally wanted to go with 1920 x 1080.
My suggestion would be to try a short segment and see what you think.
You may find out that the still images hold up OK even with a bit of uprezzing to get them to that size.
Either way, good luck with the project and don’t be afraid to come back if you have any other questions.

[Adrian Perez]

Thanks Mike. I will be coming back, I’m sure. I was just telling my girlfriend how amazing the internet is, allowing people like me to communicate with people like you and John. Simply amazing.

Anyway, thanks for answering.

Adrian