Max DPI with Canvas

[Ash B.S]

Hi everyone. I am looking into printing on canvas and am just wondering if people are satisfied with the results they have experienced. I shoot mostly 4 x 5 TMAX, TRI X and a little bit of EFKE 25. These are then scanned on an imacon 949. My main questions are:

What is the maximum DPI that can be printed on canvas effectively?

Can canvas give you the sharpness and quality that 4 x 5 film captures?

Do you think that canvas is better suited to smaller formats that need bigger enlargments?


I do not want to sacrifice the quality (detail and sharpness) of my 4 x 5 scans so any information on the subject would be very much appreciated. Thanks.

[Greg Lockrey]

If you are talking about ink jet printers, the convention is that 720 dpi is enough. I use 1440 myself. The reason 720 is supposed to be enough is more to do with the texture of the substrate and how it breaks up the pixals when applied. I use 1440 for all my printing work even when I charge for 720 since I don't get the application errors with using lower dpi.

[Ash]

(freaky with the username thing)

A local art printing and framing shop has a beautiful canvas printer. Something like a thousand per bottle of colour ink, and some crazy amount for the machine itself. It's a huge pro machine.

It can make wall-sized repro's of work on canvas. The quality is amazing close-up.


So in my opinion it depends on the quality of your scan, and where you are printing. This local place will require you to have a short meeting with their technician to optimise the print process so that you receive the best results for your work. This is all of course at a cost.

[Ben R]

Not sure about the DPI that Greg is using but using DPI as photoshop understands it, conventional wisdom is that most people cannot see a difference with more than 300DPI for small prints and 250DPI for over 10X8" prints.

Canvas really really hides any lack of resolution so that you can print far bigger sizes than you would otherwise reason being that the texture of the canvas looks like detail from afar and fills in the mental gaps. As canvas is mainly used for painting you don't expect to see more detail either even up close.

I went it to print some canvas at my local framer who has a canon 8000ipf printer. He showed me some 15"X15" canvases that he had just done, the inside of some ancient buildings from Mecca where he had just been on pilgrimage.. Asked me what I thought. Somthing just didn't look right but in all honesty I couldn't put my finger on it, I thought the colour looked a bit washed out, bit of a lack on tones. At no point looking at them from a 2 foot distance did a lack of detail spring to mind. Then he smiles broadly and shows me what he took them on - his mobile phone!

A bit of an extreme example but it puts canvas into perspective. I would say in all honesty that you don't need more than 150DPI of detail (you might want rezz it up to avoid jaggies) for a canvas. Rez up to 240DPI for printing.

[Greg Lockrey]

Not sure about the DPI that Greg is using

Printer resolution.

[JPlomley]

Ben, you are confusing image resolution and print resolution. Image resolution is ppi, print resolution is dpi.

The canvas I print on gives the best Dmax at 1440 dpi without over-inking. A lot will depend on the thickness of the inkjet receptor coating. I tend to use 100% cotton canvas which uses a thin coating so as to preserve the natural weave (and defects which makes every print unique). Not a big fan of polyester based canvas (texture is too repetitive/consistent, looks fake), nor thickly coated canvas which tends to hide the crevices of the weave and cracks too easily upon stretching.

[Bruce Watson]

Hi everyone. I am looking into printing on canvas and am just wondering if people are satisfied with the results they have experienced. I shoot mostly 4 x 5 TMAX, TRI X and a little bit of EFKE 25. These are then scanned on an imacon 949. My main questions are:

What is the maximum DPI that can be printed on canvas effectively?

There are two concepts here, and you don't give enough information to distinguish between them. One is the resolution of the output file, in pixels per inch (PPI). The other is the printer resolution in dots per inch (DPI) which is really more about how many ink dots the printer uses to create each pixel (there is NOT a one-to-one correspondence in conventional fine art printing).

And, as usual, it depends. On the output file resolution side the safest thing to do is to give the printer a file with a resolution that matches the native resolution of the printer, and of course the manufacturers use different native resolutions. Epson likes 360 ppi for their wide format printer, Canon and HP like 300 ppi, Lightjets like 120 ppcm (304.8 ppi), etc.

That said, all of the resizing algorithms the various manufacturers use for their printers are quite good. Sending a file with an output resolution lower than the printer's native resolution isn't really a bad thing. How much lower you can send and still be happy with the print is a matter of personal choice.

The bottom line is, the more information you send to the printer, the less interpolation it has do to make your print. To find where you personally will be happy, you'll have to experiment. That is, make prints at various output resolutions and compare the prints, see what the differences are, and what works for you.

On the printer resolution side, this varies some depending on the needs. Certainly lower resolutions print faster while higher resolutions offer more sharpness and sometimes improved gamut. And these things vary with the substrate. Typically people set their printers at around 1440 or so for fine art work, which is often the best compromise between quality and speed.

Can canvas give you the sharpness and quality that 4 x 5 film captures?

Absolutely. I've printed some 10x+ enlargements on various canvases (biggest was 150 cm wide from drum scanned 5x4 160PortraVC -- about a 12x enlargement). Very nice. Very sharp. Just a hint of grain in the clouds if you get right up on top of the print (say from 25 cm away).

There are rough textured canvases and smooth textured canvases, and other fabrics besides canvases to print on. They all have their appeal and their usefulness.

Do you think that canvas is better suited to smaller formats that need bigger enlargments?

No. As you go above around 10x enlargement images begin to fall apart. Doesn't really matter what the film format is. The level of enlargement is key. And canvas won't really hide this. If you don't have enough information to feed to the printer, you don't have enough information. Nothing is going to change this.

I do not want to sacrifice the quality (detail and sharpness) of my 4 x 5 scans so any information on the subject would be very much appreciated. Thanks.

I know people who love to print highly detailed images onto highly textured papers and canvases. You don't really loose sharpness as much as you gain texture. Whether or not this works for you is something that you'll have to experiment with and decide for yourself.

[Gordon Moat]

Since you stated very large professional machine, the general file preparation that works for offset tends to work well for very large inkjet. I have seen canvas prints from ColorSpan that came from 300 ppi files at the printing length and width that looked fantastic. Many of these large machines are accurate to 2540 dpi dot placement, but you don't want to feed it such huge files. The image files on large machines are often run through a RIP, so unlike some wide Epson printers the functional usage does not involve second guessing the dot placement specification (1440 or some multiple). Anyway, the place that prints these should have enough experience to recommend file settings to you.

Remember that canvas is not very smooth, and tends to scatter light more than paper. That will affect contrast and apparent sharpness. Dot gain (basically think of this as the spreading of each ink droplet) will be greater on canvas than most inkjet papers, and far greater than offset printing on a press using coated stock. The other thing to keep in mind is that most inkjet canvas is less bright than many inkjet papers, and might actually not be pure white; meaning you can try adjusting the image file slightly to compensate.

Hopefully the place will be able to work with you to optimize a print. If you are not happy with the first output, then ask what could be done to help improve a print, or ask if they will try a reprint. Some of the really large machines are quite low on cost per sq.ft., though there is the time consideration for the operator.

Ciao!

Gordon Moat
A G Studio

[Ash B.S]

Thanks for the responses guys there very helpful.

Ash