Import, Export and archiving with Chroma Subsampling

me_again wrote on 6/7/2024, 5:52 AM

Greetings,

(Not sure if this is strictly Movie Studio but as this is for use with MS 2025 I thought I'd put it here. If incorrect, please transfer it to where it should be - thanks.)

I'm dabbling in what I can only call The Dark Arts and creating a slideshow with photos scanned from a Kodak Instamatic camera and, quite frankly, the quality is dire so I've scanned the negatives (I have a 35mm slide/negative scanner) and the quality is slightly better.

I've scanned using Chroma Subsampling YUV 4:4:4 as I've read this is the best setting. In the past my MEPs haven't liked photos using 4:4:4 and crashed but MS 2025 seems to tolerate them quite well. So far so good

As far as I know, MEP/MS only exports as YUV 4:2:0 which, while fine for exporting as a finished ready to view slideshow (or video), defeats the object slightly of using 4:4:4 in the first place especially for archiving to lossless AVI - doesn't it?

I have recently installed the Ut Video lossless codec for the archiving purpose and it offers me 18 different configurations - RGBA, RGB, YUV420/422/444, BT 601/609 in 420/422/444 flavours, 10-bit versions etc etc.

Most of them cause MS 2025 to burp and tell me not to be silly in a computer jargon sort of way but a few do work OK giving me the choice of exporting in 420 or 422 or 444.

If I export with UTvideo 444, the quality looks good but then so does 420. A file I've exported to UtVideo AVI in YUV444 when put through Handbrake or Avidemux to convert to MP4 turn into YUV 420.

Hence the Dark Arts comment. I don't understand what's going on. I've read hours of detailed data of which I understood about three words, I've looked at diagrams with triangles, coloured ovals and circles which, while probably very interesting may as well be something drawn by my cat for all the good they are for a technology luddite like me.

I can understand wanting the best quality for archiving which I believe is where YUV 444 comes in. Fine if the original is also 444 but what if the originals to be edited are in 420 for instance. Does exporting to 444 really make things those look better or is it a waste of time?

I ask these questions because my eyesight is starting to leave a lot to be desired and I'm wondering whether this visual quality difference is similar to audio quality tests where sound is put through many gizmos and oscilloscopes (or whatever the modern version is) and "experts" can tell what machine is better than another but the human ear can't.

I've not really thought about any of this before yesterday, but starting a project with such a low quality set of photos has piqued my interest.

AndyW

I've just re-read this and it makes me look like a confused person that doesn't really know what he's talking about.

Excellent, because I am and I don't.

Comments

johnebaker wrote on 6/7/2024, 6:58 AM

@me_again

Hi Andy

Welcome to the 'Dark Side'

. . . . I've scanned using Chroma Subsampling YUV 4:4:4 . . . .

This sounds like you are scanning to jpg image, ie a lossy compressed format, is this correct?

What scanner settings are you using for:

resolution (dpi)
bit depth
colour conversion preset (if available) - may be defined as film stock
file formats are available

Try scanning a few images to a lossless format, eg bmp, png or tiff, at a resolution of 200 - 300 dpi, you get big files however no compression and maximum quality, depending on the scanners capabilities and settings, for comparison tests.

John EB

browj2 wrote on 6/8/2024, 6:31 PM

@me_again @johnebaker

Hi Andy and John EB,

I just scanned 299 photos for a relative, to jpg at 400 dpi. Should I have gone higher, say 600 dpi?

I want a few of them for part of a wedding film that I'll do at full HD. Most of the photos are going to need reprocessing.

John CB

johnebaker wrote on 6/9/2024, 1:57 AM

@browj2

Hi John

. . . . 400 dpi. Should I have gone higher, say 600 dpi?. . . .

Without going into the confusion caused by different units - DPI, PPI and LPI, which have different meanings of resolution, the scanner resolution you set, depends on the final use of the image and the limit of the grain 'resolution' of the film.

For most 'domestic' purposes film scanning at a value of 200 - 400 is a good balance between quality and file size for printing, or viewing on TV/phone/computer. Higher values give diminishing returns in quality, at the expense of larger file sizes.

As an example I had several 4k UHD 3840 X 2160 images cropped to square image of approx 2000 x 2000 px, professionally printed up to 18x18 in, (~ 48x48 cm), ie approx 'ppi' of 100 image pixels per inch of print, however the printer dpi resolution was much higher. Close up you cannot see any 'pixels'.

BTW, the 4K UHD images, as taken, have a DPI of 350 recorded in the EXIF data, this is, to all intents and purposes meaningless.

John EB

AAProds wrote on 6/9/2024, 2:35 AM

@browj2

I just scanned 299 photos for a relative, to jpg at 400 dpi. Should I have gone higher, say 600 dpi?

I'll throw in my 2 cent's worth. It depends on the physical size of the picture. For a physically small picture (or a slide, or those really old tiny prints for example) I'll scan it a much higher DPI (dots per inch) because if I blow it up in a movie/slideshow/image viewer, it'll be, relative to it's original size, much bigger. I'll do slides at 2400DPI or more. You want the dots per inch to be enough to minimise pixellation at the blown-up viewing size. On the other hand, if it is a big physical picture already, it won't be "blown up" and a much lower DPI can be used. I generally don't go below 300DPI.

The Photoshop Crop function is interesting to play with because you have to input input the physical size and the DPI you want. I find this extremely useful, being able to set both at the same time. I think that @johnebaker's 100dpi is probably a bit low.

johnebaker wrote on 6/9/2024, 4:08 AM

@AAProds

Hi AL

. . . . I think that @johnebaker's 100dpi is probably a bit low. . . . .

The approx 100 ppi I mentioned is the effective number of image pixels used per inch of photo print, ie the 2000px wide/high image was printed on an 18 x 18 inch backing.

I forgot to add that the scan setting also depends on the negative/slide size eg, for old 6x6 cm negatives I would not scan any lower than 200 ppi, which I have used, for 35mm negative/slides 300 is my minimum, again the scan setting depends on end use.

John EB

me_again wrote on 6/9/2024, 5:54 AM

@johnebaker

Greetings John, apologies for not getting back sooner but I was surprised to find out that I had lots to do on Friday and Saturday that was more important than "playing on the computer", or so she who must be obeyed informed me.

Anyway, the negatives were scanned at 400dpi and all seem to be 8 bit and you're correct, they are saved as jpgs. I'll look into that.

I can see some differences at high zoom but to me when used as a slideshow I can't see anything different really.

More playing is required methinks.

AndyW