Image quality - subtleties

[Helen B]

Here's what I'm pondering about at the moment - looking into it to see what there is to see.

There's a theory that says that one of the reasons that projected film looks different (maybe 'better') than video is that film is intermittent. The accompanying joke is that you should ask for half of your cinema ticket price back because you sat in the dark for half the film. On the other hand you saw the film at least twice, maybe three times (because each frame is shown two or three times). Jokes aside, this suggests that the visual experience of watching projected film is affected by something that we are not consciously aware of.

Similarly, when it comes to prints, there is the notion that there is a difference between a continuous tone and a tone made up of black dots on a white background, even though those dots cannot be distinguished as dots - ie the dots are smaller than we are able to resolve. The dots 'allow the brightness of the paper base through' to result in a more brilliant print. Again, the suggestion is that our visual experience is affected by something that we are not conscious of.

Any thoughts or similar observations? This suggests that a B&W print made by a seven-ink set will never have the same brilliance as one made by sensitive paper, even though a densitometer may measure the exact same values of optical density; that a black-only inkjet print will always look more brilliant than a continuous tone inkjet print. I'm not yet convinced, but it seems to be worth looking more closely.

Best,
Helen

[psvensson]

I think the higher apparent image quality of motion picture is due to the fact that it's made up of successive images, not that they're intermittent. Two images with slightly different details may combine in our brain to form a more detailed image, or something like that.

If you go to a digitally projected movie, you'll notice the lack of flicker is pleasing and doesn't detract from the image quality. As I understand it, these images are also intermittent, but at frequencies much higher than film.

[jd callow]

psvensson,
Does DV display more fps than film? There is the chance that the digital projection is interlaced which would compound the flicker -- or not?

I do agree or at least it seems logical that the succession of images on film might 'compile detail'.

There is the limitation of reflective opposed to illuminated as well as the limiting nature of creating 'tones' from solid dots.

[Joe Lipka]

An interesting question, but we might be trying to look at two different types of media to display an image. Each will have their inherent properties. But, I must confess, if you get a copy of LensWork, the images printed on those pages look just as good (maybe even better) than some photographs. I think that printing technology (and here I am talking about commercial printing, not an Epson desktop printer) is getting so good that some printers can match silver gelatin printing tone for tone. Whether they can provide that intangible property that makes a traditional silver gelatin print look better is still up for debate (to me).

[psvensson]

psvensson,
Does DV display more fps than film? There is the chance that the digital projection is interlaced which would compound the flicker -- or not?

I think the fps are the same - the digital projection comes from the same recording medium, after all. But it's not interlaced, and it doesn't have the same kind of intermittent blackouts that film projectors have. The flicker is definitely less. Color rendition and sharpness are another matter.

[Jarred McCaffrey]

I would agree with psvensson that digital movie projection is generally noninterlaced. A typical movie is 24 solid frames per second (25 in Europe). Television and video are commonly 30 interlaced frames per second. 24 fps reels have been the accepted movie distribution method in the US for years and I believe that mainstream (big budget) movies that are shown in digital theaters are normally the same 24 fps as their film counterparts, often a direct conversion from film.

It's worth noting that independent/low budget videos shown in independent digital theaters and gatherings are showing up more and more in the 30 fps interlaced video format because of the affordability of entry level pro video (digital) equipment and the widening prevailence of digital projection. In the past all distribution had to be done on film and it priced the low/no budget folks right out of the business. The game is changing every day though.

[Bob Carnie]

Helen
A very good question. I do both styles of printing , ink on paper and traditional negative to paper.
One thing I have noticed over the years is that as the negative is exposing I will look up from the easal through the lens and look at the light transmitting throuhg the negative down to the easal. By doing this I can see all the sublties of the negative from intense highlight to deep shawdow. I do this to see what I can bring out of the negative with split printing and paper grades. I feel that with transmitted light and concentrated dodge/burn paper selection bla bla bla. that I can mimic the negative> original scene more accurately.
With ink on paper I have noticed that with only one pass of the nossel head I can only mimic a reduced section of the original scene. therefore I have started to multiple hit the paper by registering the paper and passing multiple hits onto the paper. Much like the way one would flash, burn dodge in traditional printing.
Doing it in PS does not cut it as the whole scene flattens out unless you go crazy and cut multiple and complicated masks and layers.

I think the difference one notices between the two methods is that in traditional the image is transmited through the negative and in ink on paper the images is positioned .
Helen this description may not make sense but I have thought about this for awhile and am experimenting in mimicing the split printing method for inkjet.

[steve]

Video in the US (NTSC format) is 60 fields interlaced to make 30 frames. The fields are also "intermittent" in that there is a retrace period in which the screen is black or "blanked." This is the blanking period of 10.9 microseconds (+/- 0.2 microseconds) between fields. The video system, just like a motion picture, takes advantage of the human eye's persistence of vision to achieve the illusion of a continuous image display.

Video in Europe can be either PAL format or SECAM format which are totally different than NTSC.

Off-air broadcast television is not equal to film for a number of reasons having to do with the broadcast process and the degradation of the picture signal; and the problems that are inherent within the NTSC video system.

In general, before the advent of solid-state video cameras, the video picture was far inferior to 35mm film because of the edge softness in the tube sensors due to spot focus problems (electron beam would become ovalized at the edges during deflection).

Even $40,000 broadcast lenses with a $60,000 studio camera using 1-inch tubes could not equal 35mm film in either sharpness or color fidelity. The change to solid-state imagers in cameras solved the edge sharpness problem, but you still have the built-in resolution problem of 240 horizontal lines per field (262.5 per field but 12 are used at the bottom for masking and information transmission, and 10 are used at the top for masking).

You also have a color fidelity problem in the NTSC color under encoding that encodes the color under the luminance signal and then decodes it using two colors to generate three. This has been addressed in analog systems using component (Y/C) recording; and in digital using three color recording. But, transmission and display on an NTSC system takes the more accurately rendered color and destroys it by once again subjecting it to NTSC color under encoding/decoding.

One of the reasons video does not look like film is that video uses a 1:1 gamma slope for tonal reproduction. In fact, when a video camera is "tuned" to have a toe and shoulder, horizontal and vertical enhancement is toned down, the black level reset, and flare circuits opened up - an image from a video camera can be made to look like film.

I've done this on several occasions for video production houses on tight shooting schedules who wanted a "film look" for a commercial without having to rent a film camera so they could cut out the processing & film transfer delays prior to editing.

However, a real consideration is the way film is exposed as opposed to video. Film cameras use rotary shutters with a variable angle to expose the film so you get a discrete image per frame at whatever shutter angle (giving longer/shorter exposure time) is used. Standard video cameras use no shutter so you have motion artifacts that overlap and blur between fields.

The Panavision Genesis system resolves this problem by incorporating a rotary shutter into the electronic camera to match the shutter angle used with a film camera so that images can be intercut without the motion artifact differences.

I would ask this question; how does your perception of a motion picture change when it is shown on television? It was shot at 24fps but has been converted using a 3:2 pull down film chain into video that's now being presented in an NTSC format. You no longer have the intermittency of film, but the intermittency of video - so how is your "visual experience being affected by something you're not aware of"?

As to inkjet versus traditional print, they're different aesthetics. If you were familiar with hand printed lithographs (from stones or plates), you would know that these type of ink prints are not continuous areas of color either as there is a grain to either the stone or plate that can be seen in the final print with a 10x printer's loupe.

This gives a "sparkle" to the inked areas when compared to an image from something like a linoleum block print which can make 100% solid ink-filled areas. No inkjet print is ever "continuous tone." It can't be, anymore than a fine art lithograph is continuous tone. No matter what inkset is chosen (seven color, eight color, all black quadtone, etc.) - the image is going to be made up of very small dots just like a photographic image is made up of very small grains.

So now we get to the final part of your post which is really confusing.

"This suggests that a B&W print made by a seven-ink set will never have the same brilliance as one made by sensitive paper, even though a densitometer may measure the exact same values of optical density;"

This statement seems to address inkjet versus "sensitive paper" (I assume you mean a metal halide based photographic paper of some type) discussion.

What mechanism (the unknown one?) suggests this is not possible IF a densitometer measures the same optical density range. How is the "brilliance" (and please define that) lessened? Please relate this back to your impression of the difference in experience between seeing a motion picture projected and the same one on television.


"that a black-only inkjet print will always look more brilliant than a continuous tone inkjet print. I'm not yet convinced, but it seems to be worth looking more closely."

Here's the one where I'm really confused. What's a continuous tone inkjet print; and what's a black only inkjet print?