Interpolation for large prints

I have a 12x18" print done yesterday, for the most part it looks great, and at the correct viewing distance there are no issues with it.

However, I can't help think that with some more care I could get a better job. Pixelation or jaggies are not the issue, it is that 'digital look' around detail that I believe is caused by the JPEG algorithm.

Here is the process I went through (Photo shot at ISO100 to avoid noise):
- RAW image dowloaded from camera
- WB and minor exposure corrections made in DPP
- JPEG saved at highest resolution from DPP
- JPEG opened in Photoshop
- Upsampled to 300dpi at 12x18" (bicubic)
- Despeckle filter run to cleanup (still a little jaggie after upsample)
- JPEG saved out of Photoshop at highest quality
- Printed on Fuji Digital Frontier

Now I thought the first thing I could do would be either to do the RAW conversion in Photoshop, or save it as a TIFF from DPP to avoid any JPEG noise, the bit I am not so sure about is the upsample. There is also an chance the Frontier is doing something here as well between the kiosk and the printer (this is "have fun with Frontier" week for me ).

Any ideas?

any chance you can scan/photograph the image so we can see

I might be able to, it won't fit in the scanner, and I am reluctant to take it out of the packaging (it is not for me) in case I get prints on it (I do have some cotton gloves somewhere for that).

I actually had another thought that could be affecting the image, I am adding some sharpening in DPP, I have noticed that too much sharpening can look like too much JPEG compression.

Your workflow looks fine, though TIFF in the middle would be better - though I doubt it makes any real world difference. I've found the less I mess with upsizing and noise reduction for most images, the better they look, so I just leave them alone now, even for customer prints. One 30x16" I did for a customer I did noise reduction and sharpening on, it looked really bad printed. When I had it printed again and didn't do either it looked great. Maybe i'm just not good at it, but doing nothing works for me.

I tried the 10% upsize method, I saw no difference. I think it's a holdover from the olden days, before the bicubic resizer in photoshop. Try it for yourself and make up your own mind.

I'm trying to understand why you'd need to upsample? Is it a tight crop? Maybe it would be better to try one without resampling.
I don't see a sharpening final step? Maybe there's too much? You could try selecting the most important part of the image & just sharpening that.

Pete - probably no help here - but we get great 10x13/11x14 prints from our 4 mg. Canon original 1D frames - sweet 16x20/20x24 sizes from our Mk.2 (8 mg) frames going to 16 bit Tiffs from Raw in DPP. If PS %110 stairstep uprezzing isn't work for you, resize in DPP when processing from Raw to 16 bit tiff. Make any enhancements in 16 bit then exit to 8 bit + sharpen for Frontier printing. Might work for you - gives us some great stuff.

I am upsampling to avoid jaggies, the original image has no cropping.

The sharpening is done in DPP, is it best to leave it to last?

First what camera are you using? I too was wondering why you upsampled as this (to my eye) generally reduces the quality of the image as the software is adding info that wasn't in the original image. Upsizing may also cause the jaggies you are seeing. Don't look for jaggies at 100% viewing or more. When viewing on screen I don't view at any more than 50% generally. I have 19" x 13" prints that look stunning at 180ppi.

Sharpening should always be the last thing to do.

Try again following this

- RAW image dowloaded from camera
- WB and minor exposure corrections made in DPP
- TIFF saved from DPP (No sharpening) - Save as a 16bit TIFF for best quality image
- TIFF opened in Photoshop
- Do any further PP amendments that you feel suitable.
- Do not resample. Amend the print size (leave the resample button unchecked) or crop at 18"x12" and leave the resolution blank. If you are using an 8Mp image you'll be able to print at 194.666ppi which is plenty of resoltion for an 18x12.
- I never use the despeckle filter on an image straight from the camera. Makes it far too soft. Why do you need to clean up an ISO100 image?
- Sharpen using USM (my settings are 150/1 for a highest quality image but maybe 150 is too high).
- TIFF saved out of Photoshop at highest quality (12) JPG.
- Print on suitable paper.

I agree with EOS_JD that sharpening should be the last thing in your workflow.
When it comes to upsizing make sure you use Bicubic smoother. Downsizing use Bicubic sharper. Also do not try to upsize in one step. I tend to intorpolate in 25% increments. Same goes for downsizing. Try to work in Tiff/PSD format as much as possible. If you need to convert to Jpeg do so at the end.

When to sharpen really depends on the type of sharpening you do. I run up to a dozen layers with sharpening at different points in the workflow. Here are two great resources for sharpening:
http://www.thelightsri​ghtstudio.com …nYourSharpening​Skills.pdf
http://www.ronbigelow.​com …les/sharpen1/sh​arpen1.htm

IMPO - I never save to JPEG and then do further editing on an image. I think that's one area of you workflow that I would change. IMPO I would save the image as a PSD file - the conversion to JPEG means 8bit instead of the captured 12bits - keep all the data until you now longer need it.

Anyway I would try again working from a PSD file and follow the instrustions in my post in the link below (it's really copied from S. Kelby book).

https://photography-on-the.net …?t=118609&highl​ight=kelby