Pages: [1]   Go Down

Author Topic: Re-sizing and re-sampling??  (Read 4007 times)

Mark F

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 365
Re-sizing and re-sampling??
« on: October 21, 2010, 12:15:51 pm »

Two very experienced photographers who use PS but not LR asked if when printing in LR, whether an image can be "re-sized without re-sampling"?

I did not understand the question so they gave the example of changing a rectangular image into a square. I thought they were speaking about cropping but they said no, that with PS re-sizing is possible but the image must be re-sampled. The image is either compressed or stretched causing distortion but depending on the image it may work.

Can LR do this and if so, is re-sampling required? And what is "sampling" anyway?

Thanks.
Logged
Mark

Schewe

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 6229
    • http:www.schewephoto.com
Re: Re-sizing and re-sampling??
« Reply #1 on: October 21, 2010, 12:53:53 pm »

When printing in Lightroom you can resize an image without resampling. As long as the Print Resolution option in the Print Job panel is unchecked. You can see what the image size and pixel density will be by making sure the Dimensions check box is checked in the Guides panel. That will show both the image size and current resolution at the top of the preview.

You can also resample (interpolate) the resolution up or down by clicking on the Print Resolution option and entering in a PPI resolution. Depending on the image's native resolution (the actual PPI of the image) the entered resolution number will either be an up or down sample of the image. You can up-sample an image up to 720PPI in LR 3. As long as the native resolution of the image is between 180-480PPI, there may not be much benefit to increasing (up-sampling) an image for printing. However, images with a lot of high frequency image data or strong high contrast diagonals or circles may benefit from some up-sampling since the up-sampling occurs before the final output sharpening. You can test this on your own images to see if you see any difference.
Logged

bradleygibson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 828
    • http://GibsonPhotographic.com
Re: Re-sizing and re-sampling??
« Reply #2 on: October 22, 2010, 02:42:43 am »

A simple way to think of this whether you want to resample in your application or via the printer driver

Resampling refers to the former, and their use of "resizing" would seem to refer to the latter ("resizing" in the above context would mean "tell the printer driver what output resolution you want, and it will do the necessary resampling").
Logged
-Brad
 [url=http://GibsonPhotographic.com

eliedinur

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 328
Re: Re-sizing and re-sampling??
« Reply #3 on: October 22, 2010, 04:03:43 am »

Resizing is changing the print size, or what PS calls the "document" size, without changing the number of pixels in the source image. Since ppi, pixels per inch, is a function of these two factors it will change in a direct relationship to the change in print dimensions.
Resampling is changing the number of pixels. Usually the print size is fixed and the ppi is adjusted, which causes the change in pixel dimensions to produce the target ppi.
Logged
Roll over Ed Weston,
Tell Ansel Adams th

hjulenissen

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2051
Re: Re-sizing and re-sampling??
« Reply #4 on: October 22, 2010, 05:54:22 am »

I think that this line of thought (and use of "dpi" generally) cause more confusion than usefulness.

An image sensor, a display and (more or less) a printer use a fixed grid for its smallest image elements. If you want the pixels of a 22 megapixel "FF" sensor to fill an A4 sheet, you will have to do image resampling somewhere along the chain. The question only is where, and how good.

Which brings me to a favorite annoyance of mine: What OS/gui-designer decided that unless I check some boxes, I will want to print my images at some dpi, meaning that it will cover 2 pages or 0.5 page? I would guess that about 1% of users need that function. The rest of us have an image-file, a piece of paper and want the paper filled with image goodness (correct aspect ratio of course). I dont know how many sheets of photo paper I have wasted in Lightroom when those selections magically jump to the wrong value.

-h
Logged

Mark F

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 365
Re: Re-sizing and re-sampling??
« Reply #5 on: October 22, 2010, 11:25:34 am »

Thanks to all - I think I'm starting to get an understanding of this. But can LR change the print size without changing the number of pixels in the image so that the image can be either compressed or stretched? I've been looking at the various panels and also at the Martin Evening and Kelby books and do not see how to do it.
« Last Edit: October 22, 2010, 11:27:26 am by Mark F »
Logged
Mark

JRSmit

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 922
    • Jan R. Smit Fine Art Printing Specialist
Re: Re-sizing and re-sampling??
« Reply #6 on: October 24, 2010, 04:57:08 am »

Thanks to all - I think I'm starting to get an understanding of this. But can LR change the print size without changing the number of pixels in the image so that the image can be either compressed or stretched? I've been looking at the various panels and also at the Martin Evening and Kelby books and do not see how to do it.
When choosing a paper template, it has the paper dimensions, the print setup, and 1 or more frames defined. The frame is the image placeholder. The right panel in LR shows you the dimensions of this frame.

LR placs the image in a placeholder and thus adjust the image size (compresss or stretch) to fit into the frame.

In the colormanagment options, you can specifiy also the ppi value to use. Note that ppi is pixel per inch(on the print!),
whereas dpi is the number of ink-dots the printer uses per inch to print, regardless of the ppi setting.
The dpi is a given of the printer and can be set in the printer dialog panels.
Printer brands use a default ppi for their optimisations, HP is 300ppi (a multiple of 150 actually), Epson is 360ppi(multiple of 180 actually). So depending on your printer you just set it to this default/optimised value.
I use 300 for my HP. This is regardless of the physicl size of the actual print.
Note: In the (recent) past printing functions where not very optimal, and deviating from these optimal values could introduce moire like artifacts. I do not know if this is still the case, but i simply stick to the default optimal ppi settings for given printer brand, better safe than sorry here.
Logged
Fine art photography: janrsmit.com
Fine Art Printing Specialist: www.fineartprintingspecialist.nl


Jan R. Smit

Dick Roadnight

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1730
Re: Re-sizing and re-sampling??
« Reply #7 on: October 24, 2010, 10:07:38 am »

It seems to me that software is designed to give you the worst possible result, while trying to look helpful...

If you want the best possible print you have to over-ride the default settings and print pixel to pixel, so that the print pixel dimensions are the same as the original camera pixel dimensions, at the default printer resolution (or a multiple there of)... and if you print 18" * 24" from a 60Mpx chip at 360 original camera pixels per print inch you only crop off a very few pixels, and the result should be optimum.
Logged
Hasselblad H4, Sinar P3 monorail view camera, Schneider Apo-digitar lenses

JRSmit

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 922
    • Jan R. Smit Fine Art Printing Specialist
Re: Re-sizing and re-sampling??
« Reply #8 on: October 24, 2010, 11:31:42 am »

It seems to me that software is designed to give you the worst possible result, while trying to look helpful...
May be my earlier statement was not complete enough. What i meant was that if you send an image to print at 400 ppi to a printer which is made for 300ppi it can cause moire like artifacts on the print. At least in the past this could occur with some print solutions, not neccessarily true for Lightroom.
So if LR resamples the image to, for given example, 300 ppi, this moire like artifacts will for sure not occur. I would say this is a good solution.


If you want the best possible print you have to over-ride the default settings and print pixel to pixel, so that the print pixel dimensions are the same as the original camera pixel dimensions, at the default printer resolution (or a multiple there of)... and if you print 18" * 24" from a 60Mpx chip at 360 original camera pixels per print inch you only crop off a very few pixels, and the result should be optimum.

Perhaps true, but in my opinion not very useful. Being able to print to a given printsize is what i want and LR does a very good job of that.
Logged
Fine art photography: janrsmit.com
Fine Art Printing Specialist: www.fineartprintingspecialist.nl


Jan R. Smit

Dick Roadnight

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1730
Re: Re-sizing and re-sampling??
« Reply #9 on: October 24, 2010, 11:51:59 am »

...Perhaps true, but in my opinion not very useful. Being able to print to a given printsize is what i want...
I have a 24" printer, so my given print sizes are 18 * 24" and 24 * 36", and I can print these sizes at 360 and 240 original camera pixels per print inch, without printer moire, re-sampling or giving the software any opportunity to degrade the image, and that I consider useful!
Logged
Hasselblad H4, Sinar P3 monorail view camera, Schneider Apo-digitar lenses

Mark F

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 365
Re: Re-sizing and re-sampling??
« Reply #10 on: October 24, 2010, 04:26:17 pm »

When choosing a paper template, it has the paper dimensions, the print setup, and 1 or more frames defined. The frame is the image placeholder. The right panel in LR shows you the dimensions of this frame.

LR placs the image in a placeholder and thus adjust the image size (compresss or stretch) to fit into the frame.

Sorry to be dense here, but I'm not following you.  Say I choose Super A3/B 13x19 under Page Setup. Ignoring the margins, that fills the paper with the entire uncropped image. Now say that I want to print the same uncropped image full frame on a sheet of 8x10 paper. When I choose 8x10 under page setup LR automatically adjusts the margins so that the longer dimension fills the 10" but leaves a wide margin on the 8" side. What should I have done to fill the entire sheet by stretching one side of the image?
Logged
Mark

Roy

  • Full Member
  • ***
  • Offline Offline
  • Posts: 196
    • http://
Re: Re-sizing and re-sampling??
« Reply #11 on: October 24, 2010, 08:02:26 pm »

...say that I want to print the same uncropped image full frame on a sheet of 8x10 paper. When I choose 8x10 under page setup LR automatically adjusts the margins so that the longer dimension fills the 10" but leaves a wide margin on the 8" side. What should I have done to fill the entire sheet by stretching one side of the image?

You seem to wish to change the proportions (aspect ratio) of the image to fit an arbitrary aspect ratio such as the 4:5 aspect ratio of 8" by 10" paper. You cannot do that without re-sampling.

You can do it indirectly in Lightroom by exporting the image and changing the proportions in the export process, then re-import it to your catalog.

Or, in Photoshop, Image>Image Size, uncheck constrain image proportions and make it any size by any size you want. This will resample the image and you can also choose the resulting pixels per inch.
Logged
Roy

JRSmit

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 922
    • Jan R. Smit Fine Art Printing Specialist
Re: Re-sizing and re-sampling??
« Reply #12 on: October 25, 2010, 04:11:24 am »

Sorry to be dense here, but I'm not following you.  Say I choose Super A3/B 13x19 under Page Setup. Ignoring the margins, that fills the paper with the entire uncropped image. Now say that I want to print the same uncropped image full frame on a sheet of 8x10 paper. When I choose 8x10 under page setup LR automatically adjusts the margins so that the longer dimension fills the 10" but leaves a wide margin on the 8" side. What should I have done to fill the entire sheet by stretching one side of the image?
The way LR "fills" the frame with the image of given proportion is also definable ("zoom to fill", "rotate to fit"). In essence it means it shows in actual proportions scaled to fit the frame by either the width or heigth fit within the frame. Special case here is that the proportions of image and frame match (e.g.: 2x3).
If "zoom to fill" is ticked it will zoom to fit the frame, thus cutting of some portion of the image.
Uncropped image proportions depends on the camera (2x3, 4x5, or ...) and may or may not be the same as the paper dimensions (13x19 =~ 2x3, 8x10 =~ 4x5).
Here you have to make a choice, either crop the image ("zoom to fill", also see note below), or do not tick the "zoom to fill", but play with the frame borders to get the size on the print you want. In most cases you end up with a uneven margin width on the paper print.
(To control the crop, use in LR the crop function in Development mode, use proportions of the paper),
Logged
Fine art photography: janrsmit.com
Fine Art Printing Specialist: www.fineartprintingspecialist.nl


Jan R. Smit

Mark F

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 365
Re: Re-sizing and re-sampling??
« Reply #13 on: October 25, 2010, 04:54:17 pm »

So to get back to the original question that I was asked, as I understand it, LR will not do what they want and they should stick with PS. 

Thanks to all for your help.
Logged
Mark
Pages: [1]   Go Up