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Author Topic: To Resize or not to Resize Photos in Lightroom  (Read 4178 times)
free2australian
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« on: January 23, 2013, 06:43:03 AM »
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I Have a Mac and Lightroom 4

Camera is a Nikon D700

When speaking to a friend re sizing a photo in light at the highest resolution or to resize for Lab printing he advise me the following:

Resizing an image only is important if you need it at a particular resolution.  For example if you MUST have an image at say 300dpi and it has to have certain physical dimensions.  Then you have to resize it.  That is very rare.  When printing all that is important is the dimensions in pixels as the printing software takes care of the physical size.  So you ignore everything about resizing an image.  Just save a file in jpg format at the highest resolution and adjust the compression so that the file size is around the size that you want.  SO you might have to use a compression setting of say 10 rather than 12.

Is he correct?  If so what would be the highest resolution for this camera?


Be grateful for further clarification to his remarks

Sue
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Walt Roycraft
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« Reply #1 on: January 23, 2013, 07:38:30 AM »
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Hi Sue,

I have been listening to the LR4 tutorials, C2P tutorials and reading Jeffs book "The digital Negative".
So lets see if anything is sinking in.

If I understand correctly, go to the print module and size your image there(of course after soft proofing has been done). Check print resolution box which should be 360ppi.
Choose what media type(glossy, mat etc) sharpening(usually standard) but to your taste.

Then choose print to jpeg and send that file to the lab.

Hope this helps.
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Mac Mahon
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« Reply #2 on: January 23, 2013, 02:52:10 PM »
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Resizing an image only is important if you need it at a particular resolution.  For example if you MUST have an image at say 300dpi and it has to have certain physical dimensions.  Then you have to resize it.  That is very rare.  .....  So you ignore everything about resizing an image.

I'm not sure your friend is right.  It's quite usual when you send a print out to want it at a particular size:  A4, 17X22, or whatever.  It's more rare, in my experience, to want to print at exactly the image data pixel dimensions regardless of physical size.

Just save a file in jpg format at the highest resolution and adjust the compression so that the file size is around the size that you want.  SO you might have to use a compression setting of say 10 rather than 12.

Is he correct?
IMHO, No.  I would not use any compression at all.  Whatever else JPEG compression does, it does not improve your image quality.

I would use Lightroom's Print module to set up my print dimensions in the layout panel, then in the Print Job panel I would select print to JPEG file, and choose the file resolution recommended by the lab:  300ppi or 360dpi.  Then choose JPEG quality 100%, and let Lightroom do the resizing for you.  It's routines are as good as, or better than, any other resizing software out there.

(PS you can also choose to do this in the EXPORT panel in the Library Module, but I find the Print Module more intuitive.  YMMV.)

Cheers

Tim

PS II:  I'll have to let a Nikon expert answer your camera resolution question.
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Jim Kasson
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« Reply #3 on: January 23, 2013, 03:36:54 PM »
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Sue,

If you print from Lightroom, it will resize the image to the printer resolution you pick in this dialog:



Pick the native printer resolution of the driver. For most Epson printers at most settings, that's 360 ppi. Otherwise, the printer driver will resize the image using nearest neighbor interpolation, which doesn't give the best quality.  Lightroom's resizing algorithm has improved in LR4; it's pretty good now, but it's still not up to the state of the art.

See this for some detail.

Jim
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free2australian
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« Reply #4 on: January 24, 2013, 02:07:47 AM »
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Hi Tim and all

Thanks for your responses.  I do not print my own photographs and only send them to an on-line lab to print.

What you are saying instead of using the Export module in Lightroom 4 I go instead to the Print module and set up my dimensions there.    I did not know that one could export and not print from the Print module.   
I  have attached screen shots of the print module  window + window on to create the print.

1. Do  I save the "Create Print" to my desktop?
2.  Do I leave the rest of the information in the window as is, if not, what do I need to change ?3. 
3.  As I am not using my printer to print I then use 300 ppi?  >  Is this correct, is'nt the requirement dpi  - Lab prints at 300 dpi
4.  Where do I change the resolution within the print module


5.  Do I need to change to A3 if I am wanting a 10x8 or 8x10 print? - If so where do I change this?


Sue
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free2australian
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« Reply #5 on: January 24, 2013, 02:09:32 AM »
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Adding to my previous post - for some reason only one screen shot was attached.  Here is the other attachment

Sue
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Jim Kasson
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« Reply #6 on: January 24, 2013, 10:50:29 AM »
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Sue,

1. Save the print file where ever you can find it easily.  You'll be emailing it to the printer or ftping it, right?

2. The Print Job dialog box looks like this:



From top to bottom:

a) Pick JPEG File

b) Set the file resolution (aka print resolution) to whatever your printer suggests. If they say "dpi" (dots per inch), assume they mean "ppi" (pixels per inch). From what you say, it sounds like 300 is the right number.

c) Set print sharpening to taste. Try Standard for openers.

d) It you're having them print on glossy paper, set media type to Glossy. Otherwise, pick what seems close.

e) Set the JPEG Quality slider to the highest valuse that gives an acceptable file size.

f) Unless you're playing with the print borders, leave the Custom File Dimensions box unchecked. Lightroom will respect the image dimensions you set up in the main screen, but will not create any white space around the image. If you do check this box, Lightroom will create an image of the size specified in  Custom File Dimensions, with your image inside it. Try it and see, looking at the jpeg image that LR creates with Photoshop or some handy image editor to verify that. You should check with your printer before specifying custom file dimensions the same size as the paper you're printing on; they may not be able to handle this "full bleed" image. 

g) Ask your printer what the Color Management settings should be. sRGB is safe, but won't allow you to print the full range of colors that your printer can attain.

h) If your prints come back too light, too dark, too flat, or too contrasty, you can mess with the Print Adjustment controls.

4) See b) above.

5) See f) above.

Does that help?  Don't forget to look at the images before you send them off to the printer.

Jim
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Jim Kasson
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« Reply #7 on: January 24, 2013, 05:37:10 PM »
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Sue,

At the risk of giving you unwanted advice, Iíd like to back away from the problem you raised and be more general.

What follows assumes that you are a fairly serious photographer, which I think is likely considering where you posted your question.

First, you might consider whether you want to use a printing service at all. Soft proofing is not bad, but itís no substitute for a real print. If you had your own printer, you could make real hard-copy proofs, and get precisely the results you want, not just something close.

Second, although I havenít used a printing service for more than ten years, I remember them as falling into two classes.

The first kind attempted to offer a precise and unvarying process, and left it to you to use it how you would. That meant that you really should use their color profiles (otherwise, you canít soft-proof), and you should send them a file at native resolution. Thatís the context in which I made my earlier post.

The second kind of printing service pretty much handled the image editing. You told them what you wanted, and they did the rest Ė tone control, color management, white balancing, spotting, etc. These services were happy to work with the file at camera resolution, and, since they were experts, were perfectly capable of changing the resolution to match the printer in an optimum way. Iím thinking of people like Mac Holbert and outfits like Nash Editions.

There may be printing houses that have intermediate levels of service.

As you can see, the right answer to your original question depends on the services offered by your printer, how much you trust them, and how much control you want to have.

Jim
« Last Edit: January 24, 2013, 08:02:34 PM by Jim Kasson » Logged

free2australian
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« Reply #8 on: January 25, 2013, 01:41:34 AM »
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Hi Jim

thanks for your input

I may be a series photographer but am so non-techical all that stuff goes over my head.

About  8 years ago I bought my printer Epson  Stylus Photo R800 with thoughts of printing my own stuff . 

Inks are just too expensive.

The easy and simplest way out for me is the on-line Labs  This  is not withstanding my difficulties with the  compression and dimension  pixel stuff for the optimal print - that side of the brain seems non-existent only the creative side.

So far I have been  happy enough with the prints I receive back from the on-line lab.

thanks again

Sue
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elied
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« Reply #9 on: January 25, 2013, 03:57:12 AM »
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Sue,
If you want to keep it simple, Lightroom does simple very well. Forget about the Print module that unnecessarily (for you) complicates things. Once you have decided what size print you want, crop your image to that ratio. Then simply export a jpg. Set compression to 76, LR's recommended setting, and the color space to sRGB. Check the Resize box (your friend was wrong - if you do not resize, the lab will and LR's resizing + output sharpening is as good as and possibly better than the lab's and you have the advantage of being able to see the enlarged and sharpened version before you send it off). Set "Long Edge" and "Inches", then type in the long dimension of the print you are ordering. "Resolution" is 300 ppi. "Sharpening" is "Standard" for the type of paper. That's it, fast, simple and reliable.
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free2australian
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« Reply #10 on: January 25, 2013, 06:03:10 AM »
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Thank you

I gather that the  compression of 76 is only for the web ( to make the photo smaller to upload).   Would not compression set at 76 downgrade the photo for photo competitions and for Lab printing?

Should the Resolution be 300 dpi not 300 pip, as this determines a physical print size .  Possibly you mean using inches instead of  dimensions in Pixels.  Pixels is usually dpi.

Sue
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elied
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« Reply #11 on: January 25, 2013, 07:16:11 AM »
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Thank you

I gather that the  compression of 76 is only for the web ( to make the photo smaller to upload).   Would not compression set at 76 downgrade the photo for photo competitions and for Lab printing?

For most images 76 is the best balance between size and quality. Above 76 the increased quality is slight but the size increases more rapidly. If size is not a consideration (you have a fast upload speed and are not sending large numbers of files) you can play it safe by setting 100, but in truth the quality loss is slight at anything in the 72 to 93 range (94-100 is all the same). Personally, I compromise by setting 85.

Quote
Should the Resolution be 300 dpi not 300 pip, as this determines a physical print size .  Possibly you mean using inches instead of  dimensions in Pixels.  Pixels is usually dpi.
For historical reasons, throughout the imaging industry the term DPI (dots per inch) is used to refer to a variety of different devices. Its origin is 70-80 years ago when CRT television screens had phosphor dots per inch. It is also correctly used today to describe inkjet printers which lay down dots of ink on the paper (typically 1440 dpi for Epson printers). But when talking about digital images we are interested in the number of pixels we have available for a given print size and, therefore, the term PPI (pixels per inch) is more accurate, despite the fact that many people and application UIs continue to say "dpi". If you look at the LR Export page, you will see that it does say "ppi".
The ppi does not determine the print size, it is the other way around. The print size is a given, you chose what size print you want. The number of pixels in the image is also a given, determined by your camera, your cropping and your resizing. Ppi is the relation between them. Think of it as being like MPH, miles per hour in your car. The mph your car can do does not determine how long you can drive, it can be an hour or 5 hours or ten minutes.
A printer needs to be fed a certain number of pixels per inch of paper in order to create the matrix of ink dots it will lay down or, in the case of commercial print machines, the matrix of dots of laser light. For those lab machines it is usually 300 ppi that they need, so the first step in the lab's workflow is to resize all images to 300 ppi. As I wrote above, you are probably better off doing it in LR rather than leaving it to the lab. If you tell LR the number of inches in your print and 300 ppi, it will resize your image to the required number of pixels without you having to do the calculation yourself.
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Mac Mahon
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« Reply #12 on: January 25, 2013, 11:20:20 PM »
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Thank you

I gather that the  compression of 76 is only for the web ( to make the photo smaller to upload).   Would not compression set at 76 downgrade the photo for photo competitions and for Lab printing?

Should the Resolution be 300 dpi not 300 pip, as this determines a physical print size .  Possibly you mean using inches instead of  dimensions in Pixels.  Pixels is usually dpi.

Sue

Sue

I think you are right.  There is no need to compress the image when you are wanting to print.  Indeed there is every reason not to.  You want as much good image data as your print size and resolution allows.  Set compression to 100.

The reason I suggested using the PRINT module (as opposed to EXPORT) is that, IMHO, the print layout panel gives you a more intuitive way of setting the physical size of your image in relation to your required/desired paper size.  However, you can make a satisfactory JPEG either way.

When you choose 'Print to JPEG file' LR defaults to outputting at 300 "ppi". 

The ppi/dpi confusion is not really a confusion.  The image data is made up of pixels.  A print is made up of ink dots.  The resolution of a print is measured in dots per inch (dpi).  Printers are capable of printing only at particular resolutions depending on the electromechanical character of their print heads (which is why Canon printers and many others require 300 dpi (or 150, or 600), while Epson printers require 360 dpi (or 180, or 720))

A quality print will match an image pixel with a printed 'dot'.

If you do not take steps to match the pixels in the outputted image with the required dot resolution of the printer, the printer driver will do it for you.  The bottom line is that you can use LR to make a better job of 'resizing' your image to the right number of pixels, than the printer driver can. 

"ppi" doesn't make sense in theory but it's a shorthand for making the pixel resolution in the image to match dot resolution on the print.  You really want 300 dpi on your print.  Selecting 300 ppi in LR's 'Print Job' panel simply means that the LR will 'resize' the image to have 1 pixel per dot when the data is sent to the print head.

I hope that makes sense.

Cheers

Tim
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Tony Jay
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« Reply #13 on: January 25, 2013, 11:57:43 PM »
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...A quality print will match an image pixel with a printed 'dot'...
A good summary by Tim.
A small nitpick is just mention that in fact the printer will lay down many dots of ink to make the 'dot' that corresponds with the image pixel.
Most good printers lay down ink in the thousands of dpi - well above the ppi of the image.

Tony Jay
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free2australian
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« Reply #14 on: January 26, 2013, 05:22:53 AM »
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thanks Tim
Sue
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jrsforums
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« Reply #15 on: January 26, 2013, 10:49:59 AM »
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For most images 76 is the best balance between size and quality. Above 76 the increased quality is slight but the size increases more rapidly. If size is not a consideration (you have a fast upload speed and are not sending large numbers of files) you can play it safe by setting 100, but in truth the quality loss is slight at anything in the 72 to 93 range (94-100 is all the same). Personally, I compromise by setting 85.
For historical reasons, throughout the imaging industry the term DPI (dots per inch) is used to refer to a variety of different devices. Its origin is 70-80 years ago when CRT television screens had phosphor dots per inch. It is also correctly used today to describe inkjet printers which lay down dots of ink on the paper (typically 1440 dpi for Epson printers). But when talking about digital images we are interested in the number of pixels we have available for a given print size and, therefore, the term PPI (pixels per inch) is more accurate, despite the fact that many people and application UIs continue to say "dpi". If you look at the LR Export page, you will see that it does say "ppi".
The ppi does not determine the print size, it is the other way around. The print size is a given, you chose what size print you want. The number of pixels in the image is also a given, determined by your camera, your cropping and your resizing. Ppi is the relation between them. Think of it as being like MPH, miles per hour in your car. The mph your car can do does not determine how long you can drive, it can be an hour or 5 hours or ten minutes.
A printer needs to be fed a certain number of pixels per inch of paper in order to create the matrix of ink dots it will lay down or, in the case of commercial print machines, the matrix of dots of laser light. For those lab machines it is usually 300 ppi that they need, so the first step in the lab's workflow is to resize all images to 300 ppi. As I wrote above, you are probably better off doing it in LR rather than leaving it to the lab. If you tell LR the number of inches in your print and 300 ppi, it will resize your image to the required number of pixels without you having to do the calculation yourself.

A very good analysis of LR jpeg settings...

http://regex.info/blog/lightroom-goodies/jpeg-quality
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John
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« Reply #16 on: January 26, 2013, 05:16:01 PM »
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    Thanks jrsforums very useful information

Sue
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Mac Mahon
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« Reply #17 on: January 26, 2013, 05:21:35 PM »
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Most good printers lay down ink in the thousands of dpi - well above the ppi of the image.

Too true Tony
My Epson up to 1440 droplets per inch and Canon up to 1200 droplets per inch. One of the tricks in resizing is how to 'clump' those droplets into 'dots' so that there is a whole number of 'dots' dropped by the head as it moves.  Hence, eg 1440; 720; 480; 360; 240; 180; 120 etc for the Epson.  The optimum ratio is about balancing the amount of data sent to the printer, versus perception of continuous colour.  Jeff Schewe has a good analysis of this stuff here.
Cheers
Tim
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free2australian
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« Reply #18 on: January 26, 2013, 05:37:11 PM »
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Another thought - I have in the past only used  dpi using dimension  width and height image sizing in pixels checking resize to fit box. . Is this the best method or should I use the megapixels choice when uploading to the web?     I see there is the choice in inches which I have never used.

Which is the best for sending to the lab - pixels or inches?

sue
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Mac Mahon
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« Reply #19 on: January 27, 2013, 02:26:20 PM »
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Another thought - I have in the past only used  dpi using dimension  width and height image sizing in pixels checking resize to fit box. . Is this the best method or should I use the megapixels choice when uploading to the web?     I see there is the choice in inches which I have never used.

Which is the best for sending to the lab - pixels or inches?

sue
Sue

Exporting for the web is a whole different thing again! 
The screen resolutions that different web users have, not to mention the complete lottery over colour control, means that no matter how hard you try at your end there are no guarantees what a user will see.  For that reason I seldom upload so others will have more useful advice for you. 
The one piece of advice everyone will give is to convert to your images to the sRGB colour space before uploading, as a way of colour harm minimisation!

Tim
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