How digital pictures are enlarged: Hi all, sorry I've been looking for an answer on the net and couldn't find the answer as of yet... Are digital pictures enlarged digitally (similar...

speedmaster Loc: Kendall, FL

Hi all, sorry I've been looking for an answer on the net and couldn't find the answer as of yet... Are digital pictures enlarged digitally (similar to a digital zoom) or optically (similar to film enlarger)? I would like to understand how they keep the printing quality in very large size pictures.

Thanks

Speed

Longshadow Loc: Audubon, PA, United States

On your computer/printer - digitally.

Commercially on a digital (ink/laser) printer - digitally

Commercially on photo paper - don't know.

TheShoe Loc: Lacey, WA

speedmaster wrote:

... Are digital pictures enlarged digitally (similar to a digital zoom) or optically (similar to film enlarger)? ...

Since it is being done by a computer and not by a lens, it can only be a digital enlargement.

speedmaster Loc: Kendall, FL

Yes, i understand it can be done digitally by a computer but if we remember the DLP televisions that were not anything different from an "old enlarger" (we can think about the same of the projectors we use) it may be something similar. Doing this type of conversion may introduce noise and loss but considering that the DLP unit would be small it's use would allow a analog enlargement with better results than a digital one since optical enlargement does not criate pixelation but only loss of brightness that could be corrected by adjusting the exposition. All in theory of course, hence my curiosity...
Thanks
Speed

f8lee Loc: New Mexico

If you are starting with a digital image, then I believe the only digital-to-analog process out there is where that digital file can be used to generate a film slide - this is done using a high resolution laser that is used to expose the film, which is then developed and mounted in slide mounts. Here's a place that offers that service:

https://www.colorslide.com/

DLP (Digital Light Processing) was never an analog process - it is essentially a fancy mirror system where, rather than photosites, thousands of tiny mirrors are actuated on the surface with colored light being reflected from them to project an image (either as a rear-screen projection television like Mitsubishi used to make or in some movie theater systems). They are good, but not inherently analog, nor could it be compared to the optical enlargement of a negative or slide.

speedmaster Loc: Kendall, FL

f8lee wrote:

If you are starting with a digital image, then I b... (show quote)

Thanks for the info. I thought DLP would use a transparent screen illuminated in the back and projected through the lens. Is there any image enhancing or interpolation made when enlarging a digital picture to large sizes like 40"x 30" and larger for printing?

Cheers

Speed

f8lee Loc: New Mexico

speedmaster wrote:

Thanks for the info. I thought DLP would use a transparent screen illuminated in the back and projected through the lens. Is there any image enhancing or interpolation made when enlarging a digital picture to large sizes like 40"x 30" and larger for printing?

Cheers

Speed

Well, yes, there is. While Photoshop et al have the ability to resize upwards, there are stand alone programs like OnOne Resize that make use of better algorithms to perform the task. But don't ask me to explain how they do what they do - that's above my pay grade.

speedmaster Loc: Kendall, FL

Ok, thanks. I do work with photoshop and familiar with some of the enhancing programs. They produce good results but they are somewhat limited in their results and I was just curious how it is possible to get to those super large magnifications without showing image artifacts. Anyway, not that important, just plain old curiosity.
Thanks for taking the time to reply to my question.
Cheers

Speed

R.G. Loc: Scotland

speedmaster wrote:

......Is there any image enhancing or interpolation made when enlarging a digital picture to large sizes like 40"x 30" and larger for printing?....

As far as I know, interpolation is used every time the resolution is changed. Interpolation is a way to calculate values that fall between the values that you already have (the digital values derived from the original pixels), and that applies whether the resolution is being increased or decreased. It allows edges and gradations to be kept relatively smooth and accurate.

If you enlarge a digital image optically you are just enlarging the pixelation that's intrinsic to digital images. If that pixelation isn't visible in the original it's because it's been obfuscated by the limitations of the image reproduction process, which implies a loss of quality. If you enlarge an image like that you're just reproducing a magnified version that includes the loss of quality. Digital enlargement allows for more information to be retained, which in turn means a greatly reduced loss of quality.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Longshadow wrote:

On your computer/printer - digitally.

Commercially on a digital (ink/laser) printer - digitally

Commercially on photo paper - don't know.

Commercially on photo paper is a digital C print. It is the end process of a laser enlargement, which is exposed on light sensitive photo paper and developed in wet chemistry, the most popular being Kodak's C-41.

The machines range from "small" digital wet darkroom systems like the Fuji Frontier, to much larger production machines like Oce's Lightjet (out of production but still in use), ZBE's Chromira, Durst's Lambda - some use laser for a light source, others use LEDs.

BebuLamar

Longshadow wrote:

On your computer/printer - digitally.

Commercially on a digital (ink/laser) printer - digitally

Commercially on photo paper - don't know.

digitally as well.

kymarto Loc: Portland OR and Milan Italy

Basically if your image has more pixels than than the method by which you display it (roughly dots per inch on your print or on your display) then pixels are removed or combined, and for the contrary pixels are added. Maybe someone with more technical knowledge can explain the algorithms used in either case, as there are a bunch of them.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

speedmaster wrote:

Hi all, sorry I've been looking for an answer on the net and couldn't find the answer as of yet... Are digital pictures enlarged digitally (similar to a digital zoom) or optically (similar to film enlarger)? I would like to understand how they keep the printing quality in very large size pictures.

Thanks

Speed

Digital images are sent electronically to a digital printer. No optics are used. At least, my commercial printer does not use any optics, just electronics.

jerryc41 Loc: Catskill Mts of NY

speedmaster wrote:

...keep the printing quality in very large size pictures.

Good question, but I would say they don't keep the picture quality. That's why pictures look great on cell phones, but not so good when they're printed and hung on walls. There is only so much digital information to work with, and spreading it out decreases quality. I am not an expert in this area, but that's my story, and I'm stickin' to it.

EDIT: I missed your specific question about digital/optical. Enlarging would be done digitally, although I wouldn't rule out enlarging a digital print optically.

twowindsbear

Gene51 wrote:

Commercially on photo paper is a digital C print. It is the end process of a laser enlargement, which is exposed on light sensitive photo paper and developed in wet chemistry, the most popular being Kodak's C-41.

The machines range from "small" digital wet darkroom systems like the Fuji Frontier, to much larger production machines like Oce's Lightjet (out of production but still in use), ZBE's Chromira, Durst's Lambda - some use laser for a light source, others use LEDs.

C-41 ichemistry s for developing compatable color negative film NOT photographic prints.