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Luke1081

Uploading screenshots from video footage for news images

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Hi there,

 

New to Alamy but am a long-standing video journalist, filming news events in 4K quality. My question: Would it be possible to basically take a screenshot (ie. cut and crop a JPG from a .mov or .mp4 video) of any interesting 4K video footage and upload the resulting JPG to Alamy? Would there be any technical reason why this would not be possible (maybe in terms of size of image)? I have a Macbook Pro though no photo editing software at present - so would need some way to add IPTC data. Thank you.

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I have wondered this myself and I thought we had had a discussion thread a year or two ago on this subject - though I now can't find it.

 

I don't yet shoot 4K  so my main question, which maybe you can answer yourself, is whether the shutter speed for 4K video gives sharp enough images to be acceptable stills. In HD video the shutter speed is usually 1/50 or 1/60, which means captured stills often have a slight blur which makes them unsuitable for submission here. I don't know if the technicalities of 4K video means they have the same limitation on shutter speed and the same slight blur which makes the moving image pleasing to the eye. 

 

It may be the only way to find out is to do some test captures and examine them at 100% to see if they would pass muster the same as if they had been taken with a dedicated still camera.

 

Edit to add. If you are new to Alamy I wouldn't recommend starting submissions in this way - you don't want to start off with a load of QC fails. Perhaps upload some images on an external website and  ask the people here on their view of the likely success or failure.

Edited by Joseph Clemson

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For a UHD-1, or ultra-high-definition television (UHDTV), 4K or 3840 x 2160 = 23.7 Mb UNCOMPRESSED, so at least size-wise a 4K frame does qualify for submission to Alamy, provided the overall image quality satisfies Alamy's QC.

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Individual frames can be extracted from 4k taken at 1/50th but the subject needs to be fairly stationary to get a sharp frame. have seen a frame printed to A3 which was very good so presumably good enough for Alamy

 

Regen

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Video images (both HD and 4K) are also subject to a significant amount of compression during capture. I would be interested in seeing some example stills to see whether there is any noticeable degrading in the quality of the image. For moving pictures it doesn't much matter, but for stills it could be an issue.

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I'm sure you can look at, and capture as a still image, each individual frame in a video. The issue Geoff refers to is that, depending on the codec used, there will be a certain number of keyframes where the image is recorded in its entirety. Frames in between the keyframes are calculated from the keyframe + visual change information for each non-keyframe, making the whole video file smaller and faster in play. This is the compression  which I think may show as compression artefacts if you capture a still image from any frame. Presumably capturing a keyframe would be better, but I suspect even keyframes are compressed in their own right to save space.

 

The only way to know for sure is to capture  the still frame you desire and look at it critically at 100%. Someone new to Alamy may or may not have the skills and experience to identify QC issues, which is why I would be interested in seeing some interested person with 4K video put some stills up for all to see, and for the wise and knowledgable amongst us to pronounce judgement. I can't because I don't have the 4K kit.  :(

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