Upsampling in RAW is no different than doing it in photoshop.
You need to take into account the distance at which the images will be looked at. 300ppi is ok for when you view the images at arms length, as in a magazine. For posters you can easily go 150ppi. For street supports and billboards they go as low as 10ppi and I could perfectly imagine them going even lower as, from 50 meters away, you wouldn't even notice if each pixel was one square inch actually.
Also, why is it that people STILL confuse ppi with dpi. Dpi are a whole different concept and is the measure of the amount of drops of ink that a printer will spit per inch. It's 2013 people, we've been digital for a long time already.
In your particular case, and assuming you're not printing for far distance viewing, I would upsample (create fake pixels if you like), and then add grain/noise to create the illusion of sharpness.
I deliver the images as grainy as this, and they print perfectly in offset. This is a 100% crop of an image, and it was delivered with this much added grain/noise to the magazine you see me holding in my profile picture.
I need to print 18 mp/ 240 dpi pictures with 40 X 60 cm!
So I will need to change the image size!
What is better?
Create fake pixels to achieve the size or reduce de dpi's?
I already tried the first option, and looks great, but I can't print it now to test!
240 is good to print, that's all I ever use. But when you create fake pixels image quality does decrease, because they are fake and are more randomly chosen than the original image. I'm sure you know not to resample.
If you want to enlarge an image nondestructively OnOne Perfect Resize 7.5 will do the trick.
Sometimes you can get great results and with 150 dpi for very large prints if you have very good professional file in focus and if you upsize file on right way.
A lot of things depend from original file.
Anyway the best is if you print with 240 and 300 .
I sell a lot of very large prints up to 40 and 60 inches and if you have great original file with great focus follow these steps to upsize your file.
If your original file is out of focus there is no way to have good quality large prints.
Like someone said above there is OnOne Perfect resize ( if you don't have don't worry you can have great results and without OnOne)
Upsize your file in PS and keep 300 dpi .
When you finish copy original layer 3 times.
On first layer set blending mode to softlight and apply high pass sharpening filter , make mask and paint with brush araound where you need ( this is for large details and clarity).
On second layer set blending mode to overlay and make same steps like above
( this is for medium details )
On third layer set blending mode to linear light and again steps from above ( this is for small details) .
These steps with layers apply and after OnOne if you work , this is a MUST.
Usually I apply high pass sharpening filter with 8-9 radius for large an medium details , for small details around 1.8
You can make and radius bigger , because you will have mask and paint with different opacity , depend from your needs and taste.
Darren Green wrote: I've used interpolation for printing for years, the main keys are to be at least 300ppi and when interpolating just go up 10% each time dont try to do it all in one.
This is the practice I follow. Set your resolution to 300dpi and begin increasing pixel scale by 10%. Check the box for "Resample Image" and select Bicubic Smoother (best for enlargements). Place a light High Pass filter before print and you're good to go.
Algorithms have improved considerably since Photoshop 7. This is no longer helpful in most cases, and is probably having the opposite effect.
Actually, no, the algorithms implemented in Photoshop haven't been improved at all. There are two new variants of the bicubic scaling (smoother and sharper), but that's about it.
True, there exist a few new algorithms that work considerably better (Lanczos, Genuine Fractals, etc.), but you won't find them in PS.
By the way, Stair Interpolation (the procedure of scaling up the image in small steps) is still among the best performing techniques around. Indeed, there have been studies that show that the results achievable by Stair Interpolation are comparable to (and sometimes better than) those produced by expensive software packages (that includes GF).
I read somewhere that using bicubic sharper was better than smoother to downsize and upsize photos in photoshop. They said that bicubic smoother blurs the pixels and bicubic sharper doesn't. (10% increments) Who is right? I tried it and sharper worked best, just going by an article I read anyway.
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Marin Photography wrote: I read somewhere that using bicubic sharper was better than smoother to downsize and upsize photos in photoshop. They said that bicubic smoother blurs the pixels and bicubic sharper doesn't. (10% increments) Who is right? I tried it and sharper worked best, just going by an article I read anyway.