Print file resolution

I have always printed at 360ppi when working in colour. My understanding is that I shoukd use a multiple of 360. Does this apply with K7 and QTR. In the PZ manual it implies that the more resolution the better. It mentions printing at 1000ppi at one point. Does the 360 multiple still apply?

360 rule does not apply to Piezography curves. The Piezography curves with the QTR driver break that rule.

With a normal dithering - there is a lot of paper white that is unprinted. This is the space between dots of ink. This is especially true with low frequency dithering patterns in which a darker ink is made to look lighter by using fewer dots of ink and much more paper white. With Piezography curves, the dithering is always at high frequencies and there is never space between dots. Ever.

The space between dots is being printed in Piezography with detail. It is not being printed with a normal driver output and yes you are right - with color work anything over 360dpi is simply wasted.

But, not so with Piezography.
But resizing a file does nothing to take advantage of that.
You have to have optical resolution to take advantage of it.

At Cone Editions we drum scan medium and large format film at super high resolution.
For my own work I use a Sony A7R and enjoy more pixels…
The new Canon would not be wasted on Piezography - but you would want to have really decent glass.

Thanks Jon. So the rule is ‘don’t resize’. I’m off to try a 40mp Hasselblad file, followed by a 36mp Nikon. I’ve always hated the thiught of dumping resolution.

Don’t ever resize. Optical is EVERYTHING in Piezography… it will never be sharper if you resize - let it go to where it is in pixels. Because also, Piezography does a bang up job on 100dpi. better to let it run even if you think you do not have enough resolution… really!

Thanks Jon. If I keep it at full size, what is your preferred method of sizing for sharpening and to fit on a page. Crop to size without res, image size or what?

Sharpening is only done at 100% view or what is called pixels view in Photoshop. There, you sharpen until it looks too sharp and back off until it looks naturally sharp. There will be no dithering to break up the over sharpening as there is with a half-tone in book reproduction or with color inks using the OEM driver. So pay very close attention to what you consider to be sharp enough and not too sharp.

To size it, never select resample - keep the pixels to what you have always - letting the page setup do the resizing (it can not resample) or resizing it in Photoshop without resampling are the same. You are merely scaling the image to output size. The pixels remain the same - the printer uses more tiny droplets to scale it.

Thanks Jon. It hadn’t occurred to me that I needed to alter my sharpening. I’ve always found that PK sharpener did a great job on colour without any modification. I’ll take a closer look at it for my piezography work, so much to unlearn.

I’ve just discovered that PK sharpener can resize without resampling and that I can reduce sharpening by varying opacity. Looking good.