Forums > Digital Art and Retouching > Photo resize! Increase pixel number or reduce dpi?

Photographer

Bruno Inacio

Posts: 27

Paris, Île-de-France, France

Hello everybody.

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!

Cheers,
Thanks.

May 16 13 06:43 am Link

Photographer

sidney_k

Posts: 876

Paris, Île-de-France, France

You need at least 240, better 300-360 dpi to print well on an inkjet,
so you will need to interpolate.

edit: =create fake pixels wink

May 16 13 06:52 am Link

Photographer

Bruno Inacio

Posts: 27

Paris, Île-de-France, France

I usually print with 300 dpi's,

but in this case I was worried because it will be a big interpolation! Howerver the test looks good!

Thank you, good work.

May 16 13 07:02 am Link

Photographer

Darren Green

Posts: 1374

Nottingham, England, United Kingdom

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.

Good luck

May 16 13 07:40 am Link

Photographer

Gulag

Posts: 1253

Duluth, Georgia, US

another way to achieve that is to upsize up in front in ACR before your bring it into Photoshop.

May 16 13 08:19 am Link

Photographer

ME_

Posts: 3152

Atlanta, Georgia, US

The difference in physical size is so negligible that for such a small variance, I would just change the PPI. Nobody will ever notice.

May 16 13 08:32 am Link

Photographer

Christopher Hartman

Posts: 54153

Buena Park, California, US

Bruno Inacio wrote:
Hello everybody.

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!

Cheers,
Thanks.

I think resampling to a larger size is fine.

I print to Epson printers and use 360 ppi so I pretty much have to upsize everything except for very small prints.

May 16 13 11:09 am Link

Retoucher

FLEXmanta

Posts: 1001

Madrid, Madrid, Spain

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.

http://13j.imghost.us/vNm/Screen%20Shot%202013-05-16%20at%2020.09.21.JPG

May 16 13 11:15 am Link

Photographer

Bruno Inacio

Posts: 27

Paris, Île-de-France, France

Thank you everybody!

I climbed another step thanks to you.

May 17 13 07:14 am Link

Photographer

richy01

Posts: 153

Amsterdam, Noord-Holland, Netherlands

Depending on the viewing distance You don't really need 300 ppi...for 40x60cm you can print easily on 240...Inktjet I mean.
We print op a Epson 9700 even on 175 for prints 100cm wide

May 17 13 08:01 am Link

Photographer

WMcK

Posts: 5298

Glasgow, Scotland, United Kingdom

FLEXmanta wrote:
Upsampling in RAW is no different than doing it in photoshop.

Very wrong!!!!!!!
Raw upsamples linearly, PS gamma corrected, giving very different results.

May 17 13 12:51 pm Link

Retoucher

Peano

Posts: 4106

Lynchburg, Virginia, US

WMcK wrote:
giving very different results.

Can you post an example that shows the difference?

May 17 13 02:01 pm Link

Retoucher

FLEXmanta

Posts: 1001

Madrid, Madrid, Spain

WMcK wrote:

Very wrong!!!!!!!
Raw upsamples linearly, PS gamma corrected, giving very different results.

True.

May 19 13 10:18 am Link

Photographer

descending chain

Posts: 1270

Fullerton, California, US

Darren Green wrote:
...when interpolating just go up 10% each time dont try to do it all in one.

Algorithms have improved considerably since Photoshop 7.  This is no longer helpful in most cases, and is probably having the opposite effect.

May 19 13 12:41 pm Link

Photographer

David Nelson Photograph

Posts: 348

San Antonio, Texas, US

Bruno Inacio wrote:
Hello everybody.

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!

Cheers,
Thanks.

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.

May 19 13 12:50 pm Link

Retoucher

ST Retouch

Posts: 358

Zurich, Zurich, Switzerland

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.

Regards!

May 19 13 02:17 pm Link

Photographer

Bruno Inacio

Posts: 27

Paris, Île-de-France, France

Wow,

this is incredible, always new tricks and ideias!

Thank you everybody!

I already sent this work that I needed to resize, but some more is coming!

Thank you very much!
You're incredible persons.

May 20 13 11:56 am Link

Retoucher

Pictus

Posts: 1123

Teresópolis, Rio de Janeiro, Brazil

Interesting links...
http://www.digitalphotopro.com/techniqu … ution.html
http://www.luminous-landscape.com/forum … #msg446993
"here's a simpler guideline for Epson printers; if your image's native size is less than 360PPI, set the resolution in LR to 360 for the output resolution, if the image's native size is above 360 but less than 720PPI, set the resolution to 720PPI in LR.
For Canon and HP the numbers are 300/600PPI..."

May 20 13 02:08 pm Link

Photographer

Bernard Wolf

Posts: 28

Santa Monica, California, US

Another uprez article that will help: http://www.digitalphotopro.com/techniqu … p-res.html

May 20 13 07:30 pm Link

guide forum

Photographer

Jennifer Haggerty

Posts: 1274

Austin, Texas, US

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.

Good luck

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.

May 21 13 07:36 pm Link

Retoucher

Marcus Christopher

Posts: 91

Vienna, Wien, Austria

descending chain wrote:

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).

May 25 13 03:59 pm Link

Photographer

Marin Photography NYC

Posts: 7319

New York, New York, US

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.

May 25 13 04:10 pm Link

Retoucher

Ledo retouch

Posts: 1182

Lodi, California, US

for work we always cropped original file to finished size @ 300 ppi.
my reasoning was more pixels = better whatever way they were created
 
now after my own unscientific research, I don't resample and things
look better and I don't save files for 8r, 11r and 16r

May 25 13 06:36 pm Link

Retoucher

Pictus

Posts: 1123

Teresópolis, Rio de Janeiro, Brazil

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.

To reduce size, look http://www.modelmayhem.com/po.php?thread_id=812189

May 25 13 07:01 pm Link