Image preparation - resizing


#1
Hi all, I have been reading through The Piezography Manual 2016 Deluxe Edition in preparation of printing digital negatives and have a question about resizing the image before printing.
In Chapter 6, Image preparation (on page 35), the advice is to resize the image without actually resampling it by “unchecking the Resample Image box”. By doing this the required dimensions can be set and if the image has a high resolution the print will benefit by having the highest possible ppi automatically set for the dimensions.
This made sense to me and I thought I'd follow that advice for printing negatives too.
However, in Chapter 11, PiezoDN & The Digital Negative (on page 99), the advice is to actually resample your image - choose image size and set the resolution to fixed 720ppi.
The negatives I'll be printing come in two formats - 2000dpi scans from 4x5 film (approx. 10000x8000px) and digital captures which are 6016x4000px.
So how are other people resizing their images for print with regard to ppi? what is the recommended Inkjet Mall way?
Many thanks

#2

Dear Jason. The QuadtoneRIP driver up-samples or down-samples ever everything to 720ppi before sending to the printer. 720ppi is (of course) very different the printer DOTs (dpi) which require more dots to properly register the actual pixels (hence the need for 2880ppi on the printer).

So, if your print-size ppi ends up more than 300ppi or less/equal to 720ppi you are good: no need to do anything. If you’re image file is HUGE and you are printing SMALL and your ppi is higher than 720 than you have the option to downsample to 720ppi in Photoshop using “reduce sharper”. This will do a better job than QTR’s reduction to 720ppi. Related to Dig Negs, Photoshop also does a better job at UP sampling. So if you have a low res image and you need to get more neg detail out of it, upsample using Preserve Details.

Our upcoming dig neg driver does not reduce the pixels going to the printer and sends everything at 720ppi or higher (if the file is higher). This is only really needed for things like negatives.

tldr: Sample down or up to 720ppi in Photoshop for dig negs. Don’t really worry about it for ink on paper.


#3

Thanks for the info, I’ll keep an eye out for your upcoming driver.