let me look at you forever
May 5, 2011 4:44 PM   Subscribe

I need a (preferably free) program to pull high-quality screencaps from a DVD on a Mac.

VLC's screencap function is only pulling the images at 72 resolution. I really need 300 or better. Thanks!
posted by gerryblog to Media & Arts (13 answers total) 1 user marked this as a favorite
 
Best answer: DVD frames are 720 pixels wide by 480 (NTSC) or 576 (PAL) pixels high. That's all you're going to get, and that's exactly what VLC gives you.

If you want to change the printing DPI (i.e. from 72 to 300), then that's a totally different thing. It might pay to read the wikipedia article on DPI, or tell us why you need 300DPI.
posted by Pinback at 5:03 PM on May 5, 2011


Response by poster: It's for publication, and what the press has asked for. It sounds like I can't get what they want without going through the studio.
posted by gerryblog at 5:12 PM on May 5, 2011


Best answer: DVD images dont have a "dpi" they have a resolution - typically 720x480. You will never get more information from a DVD no matter what software package you use. The "72 dpi" you see is just a default placeholder and means nothing.
posted by The Lamplighter at 5:37 PM on May 5, 2011


Its amazing how even now designers don't understand how computer images actually work and ask for "300 dpi" even when that's meaningless.
posted by The Lamplighter at 5:40 PM on May 5, 2011


What everyone else says.

There's no such thing as "resolution" until the point where you're creating output on a screen or on a piece of paper, etc. Pixels are pixels and there are only so many of them on a DVD.

If the number of pixels isn't sufficient for the person requesting the images, then yes, you will have to source better images, most likely stills from publicity material, press kits, etc.
posted by AmbroseChapel at 5:50 PM on May 5, 2011


The reason the press folks told you this is that they are endlessly receiving sub-100 dpi artwork because it looks just fine on the screen while the client was laying it out but it'll be a pixelly mess on the page. I suspect that a screengrab from a high-resolution monitor, when cropped and appropriately sized, will work fine unless this is a full-page type of thing. Don't DVD players like VLC do some sort of smoothing when they display a 720x480 image on a 1900x1200 monitor?
posted by pullayup at 5:58 PM on May 5, 2011


Pullayup - the DPI of an image doesn't mean anything, it's how many pixels the image contains.
posted by The Lamplighter at 6:39 PM on May 5, 2011


Lamplighter, I used to be the prepress guy for a newspaper. However, I know a lot more about print that I do about video. VLC does some kind of interpolative upsampling when it is asked to display it in a window that's not the nominal size of the video, right? I know we could suggest the equivalent in Photoshop, but I don't know if the OP's up for that. Getting higher-resolution stills from the studio is madness in this situation--what the OP needs is just a smoothed-out version of the screencap. It's video reproduced in print, and nobody expects a still to be crystal-clear.

I know It's a cheap (an relatively worthless) trick as far as making an appealing printed image, and doesn't add any actual information, but it will prevent the "jaggies" that the customers complain about when a low-resolution image is reproduced in print--which is what the printer is worried about.
posted by pullayup at 7:15 PM on May 5, 2011


And, I should note that the original (720x480) screencaps will be 240 dpi--perfectly sufficient for most print applications--if they're printed at 3"x2". At what size will these stills be printed?
posted by pullayup at 7:29 PM on May 5, 2011


Shouldn't the printer be the one resizing the image, using their sophisticated software, rather than relying on whatever basic realtime filtering that VLC does?
posted by The Lamplighter at 7:32 PM on May 5, 2011


It really depends on the printer. These days it's totally possible that the printer is being given "camera-ready" (that is, ready to make a plate from) material by the vast majority of their clients--the barrier to producing PDF files, which are the lingua franca of printable images, is very, very low these days. If this is a big-money print job (a book or magazine or something) the printer is going to want an InDesign file, and at that point the customer probably already has (or has stolen) Photoshop. Photoshop IS their sophisticated software.

The thing is, the printer is interested in making sure that what they're getting really is camera-ready, that is, there's enough detail (dpi) in the images that the pattern of ink dots (which is described in lines per inch, or lpi) is large enough to subsume the grid-pattern of pixels (dpi). At "normal" print resolution of 150 lpi the magic number is 300 dpi. Hence, the figure that gets thrown around.
posted by pullayup at 7:42 PM on May 5, 2011


Also, this isn't my area of expertise, but I kind of think upsampling algorithms are upsampling algorithms. I'm not sure Photoshop's would actually be more sophisticated, or produce a noticeably better result, than VLC's, though I superstitiously always use "Bicubic Sharper." You could use an unsharp mask filter to maybe punch it up a little, but you're still making a silk purse out of a sow's ear.
posted by pullayup at 7:50 PM on May 5, 2011


It's very unlikely that VLC is doing any resizing when it's displaying full screen. The video driver offloads that, because it can be hardware accelerated. VLC hands off the frame in YUV420 or YV12 colorspace to the video overlay which has the hardware do the resizing and colorspace conversion. This is much more efficient than doing it in software. If you really want to you can force software scaling (swscale filter plugin in libavcodec for example) but this is generally not what you want. Resizing the frame in photoshop using a high quality filter like bicubic of lanczos will be unquestionably better in terms of quality.
posted by Rhomboid at 11:27 PM on May 5, 2011


« Older Need ideas for games to play and discuss in a high...   |   What are my options for permanent hair removal on... Newer »
This thread is closed to new comments.