Help needed with cropping and sizing for Prints

[RJohnston]

Correct, my Nikon creates a file 4118 pixels wide x 2758...
At a "resolution" of 300 pixels per inch...
The size of that file is 65 megs... If I tell Photoshop to display it at actual pixel size, then it shows it huge... at about twice the width of my 20" Monitor.

If I change the pixels resolution to 72, then it does not even fill half my screen when I click View at Pixel Size. There is a lot of difference in sharpness in a finished print, if you print a 72 pixel per inch in a 24 x 36 size print and doubt MPIX would print one that large, as they guarantee satisfaction and would get a lot of returns. But they print mine that large.

Yes, the large companies are getting PPI and DPI wrong. They even have articles on their websites or refer photographers to sites that have it wrong.

At 72 pixels per inch it would change the file size to about 3.7 megs... that is quite a difference. Now it is strange to me that MPIX would use 72, when they get 240 minimum from me when people order on my website. (they drop ship them)

NOW, JPGs made for Websites are 72 Pixels per inch, because Websites only display photos at 72 pixels so it is a waste of time to send larger files, they take too long to display and upload. So that may be why you are getting that size. However when I make JPGs to give to friends or relatives, I send them at 240 pixels so they can print quality prints from them.

You may be missing a setting in the program which makes your JPGs, the one for PPI so it is automatically assuming it is for a website.

IF I were you and wanted scans of negatives, Id scan them myself. You can get relatively inexpensive scanners which scan at much higher than 300 pixels per inch. Especially for 35mm, dont have a coolscan from Nikon, but its about the best scanner you can buy. Id check and see what resolution it scans. Then buy a less expensive scanner that will come as close as possible.

It could also be a misunderstanding at MPIX, they may scan higher then be giving you JPGs at 72 and someone is assuming that is what they scan at.

Try an experiment. Load a RAW file into photoshop that is the 240PPI your camera produces. Click on View, Pixel size and see how sharp it is you will probably have to scroll it to see it, then change the PPI to 72 and see the difference in size. (do not save it.)

THEN, change it back to 240 and notice the difference. If you have sharp eyes, especially if you pick a shot with text in it, you will see a loss of quality, it may not be bad, but there is a loss of sharpness.

IF you do that with an 8 bit JPG, the loss will be even greater. Each time it is saved, even without changes it loses more and more quality.

A long time ago, before I learned this shooting with a 5.6 mg Digital that produced JPGs only. Dont know why I ever bought it, Id been shooting with Nikons since the 50's. Lost a lot of very good images by making the mistake of loading them in PS and editing them. Its a hard lesson to learn.

You may also want to check your camera manual to see what PPI it creates. Some software has hidden in preferences a setting which lets you set the size for photoshop. Some have it set to 240 as the default, if your camera manual says 300, Id change it to 300 for photoshop.

[mjp321]

Originally Posted by RJohnston

Correct, my Nikon creates a file 4118 pixels wide x 2758...
At a "resolution" of 300 pixels per inch...
The size of that file is 65 megs... If I tell Photoshop to display it at actual pixel size, then it shows it huge... at about twice the width of my 20" Monitor.

If I change the pixels resolution to 72, then it does not even fill half my screen when I click View at Pixel Size. There is a lot of difference in sharpness in a finished print, if you print a 72 pixel per inch in a 24 x 36 size print and doubt MPIX would print one that large, as they guarantee satisfaction and would get a lot of returns. But they print mine that large.

Yes, the large companies are getting PPI and DPI wrong. They even have articles on their websites or refer photographers to sites that have it wrong.

At 72 pixels per inch it would change the file size to about 3.7 megs... that is quite a difference. Now it is strange to me that MPIX would use 72, when they get 240 minimum from me when people order on my website. (they drop ship them)

NOW, JPGs made for Websites are 72 Pixels per inch, because Websites only display photos at 72 pixels so it is a waste of time to send larger files, they take too long to display and upload. So that may be why you are getting that size. However when I make JPGs to give to friends or relatives, I send them at 240 pixels so they can print quality prints from them.

You may be missing a setting in the program which makes your JPGs, the one for PPI so it is automatically assuming it is for a website.

IF I were you and wanted scans of negatives, Id scan them myself. You can get relatively inexpensive scanners which scan at much higher than 300 pixels per inch. Especially for 35mm, dont have a coolscan from Nikon, but its about the best scanner you can buy. Id check and see what resolution it scans. Then buy a less expensive scanner that will come as close as possible.

It could also be a misunderstanding at MPIX, they may scan higher then be giving you JPGs at 72 and someone is assuming that is what they scan at.

Try an experiment. Load a RAW file into photoshop that is the 240PPI your camera produces. Click on View, Pixel size and see how sharp it is you will probably have to scroll it to see it, then change the PPI to 72 and see the difference in size. (do not save it.)

THEN, change it back to 240 and notice the difference. If you have sharp eyes, especially if you pick a shot with text in it, you will see a loss of quality, it may not be bad, but there is a loss of sharpness.

IF you do that with an 8 bit JPG, the loss will be even greater. Each time it is saved, even without changes it loses more and more quality.

A long time ago, before I learned this shooting with a 5.6 mg Digital that produced JPGs only. Dont know why I ever bought it, Id been shooting with Nikons since the 50's. Lost a lot of very good images by making the mistake of loading them in PS and editing them. Its a hard lesson to learn.

You may also want to check your camera manual to see what PPI it creates. Some software has hidden in preferences a setting which lets you set the size for photoshop. Some have it set to 240 as the default, if your camera manual says 300, Id change it to 300 for photoshop.

Sorry. For some reason I could not get Multiquote to work so I'll just quote everything you wrote and try to respond to most of your points. Thanks for responding to my questions, btw!!!

My Canon dSLR is just 8MP and creates a 3456 x 2304 file, which is typically a little over 2MB for a large jpeg file or 9MB for raw files. Are you saying that your camera creates a 65MB jpeg or raw file? If so, I'm just astonished!! How many MP is your camera? Or are you going by the size of the resulting tiff or PSD files after converting from the raw file? From the raw file, I can either get a 22MB tiff file (8 bit), 44MB tiff file (16 bit) or a PSD file (I've forgotten the sizes of those at the moment - it varies anyway).

As for Mpix, they did supply me with files that were 72 PPI (and on a CD, so there was no reason for them to try to make them smaller - they don't allow downloads of scanned negatives from their site - you have to either order prints from the scans or a CD archive). To tell you the truth, I've only had a few dealings with them and I'm already fed up with with their lying. On their site, they claim that the 35mm scans are at 1818x1228, 72 DPI (when they should have said PPI!), and that the resulting file size of each image would be about 6.39MB. Well, when I got single my disc with all 216 images, I knew something was wrong, because 216 images at 6.39MB should have taken up 2 CDs. Only 394 MB of the 700MB CD was used and when I looked at the file sizes of the images, they were between 1.5 and 2MB each. Also, the pixel dimensions were much higher than stated. Instead of 1818x1228, I got 3130x2075 (at 72 PPI). I emailed and complained about the false advertising on their site and got the following reply from Matt ("Mpix Community Manager"): "Have you opened the files? I think if you open them in Photoshop you will find they are 6.39MB. They are compressed when you view them on the disc." So, anyone here know about this "new technology" that allows jpegs to be compressed on a CD and magically be expanded to 6.39MB in PS? Or was old Matt giving me the runaround? Anyway, I also thought it was strange that they would do their scanning at 72 PPI, but I figured they must know what they're doing. I am coming to the realization that they do not.

Yes, I had also heard that it was a waste to make website images anything over 72 PPI. As for the large jpeg coming out of my dSLR at 72 PPI, that's what it says under Image Size in Photoshop. I was not using "save for web" or anything like that (I've in fact never used the save for web function). This was a large jpeg that came straight from the CF card to computer and opened in Photoshop. I have my camera set to record both raw and large jpeg at the same time, btw.

I will look into film scanners, if I can get better quality from it than Mpix can give me (I assure you they are scanning at 72 PPI - says so on their website and PS also confirms this).

Yup, I already knew not to save jpegs over and over. When I have to edit a jpeg, I first convert it to a tiff, then do all my editing and then save a copy as a jpeg. But most of the time, I just convert raw files to tiff or PSD (if I want to save layers), and do all my editing. I don't see how you could have lost all your quality images by saving jpegs, unless you were saving over the original jpeg file. I've never done that, luckily.

Also, I've looked through my camera's menu and manual several times and saw no setting at all for PPI. I figured that whatever PPI it gave me was inherent to the camera. I'll look into this further. All I know is that I was getting 240 PPI tiffs and jpegs from my raw files, and was surprised to see the large jpeg come straight out of my camera at just 72 PPI!

By the way, what would you think would be the largest sized print I could get from a 72 PPI image without the loss of quality becoming too apparent?

Thanks for all your replies!!! It's great having more experienced photographers on here to help us (you were shooting back in the 50's and I wasn't even born until the late 50's).

Mike

[verdesardog]

By the way, what would you think would be the largest sized print I could get from a 72 PPI image without the loss of quality becoming too apparent?


That depends on how big the file is
.... how many total pixels? An 80x100 inch 72ppi file would print just fine if you printed it at 8x10 inches ...You have to remember there are three attributes to an image size: pixel dimension, documnet size and resolution. It is only document size and resolution that you have to be concerned about when printing and pixel dimension for web hosting. (even though "standard" web images are 72ppi they can be any resolution as long as the pixel dimension is within reasonable guidelines) (when I post my photos on here I resize to 800 pixels on the longest side, I don't care what the resolution is because it doesn't matter on the web. But they are usually about 2 or 3 inches per side @300ppi which gives a pixel dimension of about 2M)


It is simple math: You can transpose those attributes to get any one.

resolution = pixel dimension / document size

document size = pixel dimension / resolution

pixel dimension = resolution x document size

So figure it: out you want an 8" x10" print, the printer says he wants 300ppi. One square inch at 300 ppi will be 90000 pixels(300x300), an 8x10 is 800 square inches so 800 x 90000 would require a file with a pixel dimension of 72M.

So, to be repetitive how large the file is that you want to print will determine how large you can print it. dpi and ppi (without document size) have nothing to do with how large you can print a file. The only thing that determines how large of a print you can make from a file is how many total pixels are in that file.

[mjp321]

Originally Posted by verdesardog

By the way, what would you think would be the largest sized print I could get from a 72 PPI image without the loss of quality becoming too apparent?


That depends on how big the file is
.... how many total pixels? An 80x100 inch 72ppi file would print just fine if you printed it at 8x10 inches ...You have to remember there are three attributes to an image size: pixel dimension, documnet size and resolution.

When I asked how large a print I can make at 72 PPI, I was referring to the sizes I was getting from my digital camera, which is 48x32 inches, or the scanned images I got from Mpix- 43x29 inches. But since those are about half of the 80x100 inches you mentioned above, I guess my 72 ppi files would make lousy 8x10s.

Originally Posted by verdesardog

So figure it: out you want an 8" x10" print, the printer says he wants 300ppi. One square inch at 300 ppi will be 90000 pixels(300x300), an 8x10 is 800 square inches so 800 x 90000 would require a file with a pixel dimension of 72M.

So, what happens when the printer wants 300ppi (lets say Mpix) and that same printer only gave me a file that was 72ppi to print? I'm still trying to figure out why they would scan those negatives at 72ppi.

Originally Posted by verdesardog

So, to be repetitive how large the file is that you want to print will determine how large you can print it. dpi and ppi (without document size) have nothing to do with how large you can print a file. The only thing that determines how large of a print you can make from a file is how many total pixels are in that file.

And I did give you that information in my original post (since there is a direct relationship between document size, ppi and pixel dimension, and I gave you 2 of those in my previous post). I was basically looking for some cutoff point where you would no longer get acceptable prints at the dimensions I had listed. At what point, in terms of PPI (when given the normal pixel dimensions and document sizes of your typical dSLR - lets say 10MP) will you not be able to get an acceptable 8x10?

What the printer asks for in terms of ppi is irrelevant, isn't it? Because I can only give them what I have, right? Or can I upsample the image somehow to get 300 ppi and more total pixels? Can Photoshop manufacture some extra pixels for me and at the same time make the quality of the print better? A stupid question, I know, but thanks for your help.

[RJohnston]

Originally Posted by mjp321

How many MP is your camera? Or are you going by the size of the resulting tiff or PSD files after converting from the raw file? From the raw file, I can either get a 22MB tiff file (8 bit), 44MB tiff file (16 bit) or a PSD file (I've forgotten the sizes of those at the moment - it varies anyway).

My camera is 10mp or ten million pixels. RAW files are interpreted to be the PPI that you want, by the software. Lightroom gives you the choice of what resolution you want. I choose 300, could even choose 600 or 1200 and can make 4800 ppi with my scanner. But beyond a point the benefit gained by higher resolution is not worth the size of the files.

Originally Posted by mjp321

To tell you the truth, I've only had a few dealings with them and I'm already fed up with with their lying.

There is a difference between lying and ignorance.

Originally Posted by mjp321

resulting file size of each image would be about 6.39MB. Well, when I got single my disc with all 216 images, I knew something was wrong, because 216 images at 6.39MB should have taken up 2 CDs. Only 394 MB of the 700MB CD was used and when I looked at the file sizes of the images, they were between 1.5 and 2MB each. Also, the pixel dimensions were much higher than stated. Instead of 1818x1228, I got 3130x2075 (at 72 PPI). I emailed and complained about the false advertising on their site and got the following reply from Matt ("Mpix Community Manager"): "Have you opened the files? I think if you open them in Photoshop you will find they are 6.39MB. They are compressed when you view them on the disc." So, anyone here know about this "new technology"

It is not "new" technology, actually has been around for a long time. JPGs by their very nature are compressed. When you create a JPG from a RAW or TIFF image, it gets reduced in size according to how you set it. The greater the compression, the greater the loss of quality. But, some images depending on several things will compress a lot without loss and others will not compress as much. Like a clear blue sky will compress a lot more than one with lots of clouds, etc... When you open it, the computer reads the commands in the file and virtually reconstructs the pixels again.

Originally Posted by mjp321

By the way, what would you think would be the largest sized print I could get from a 72 PPI image without the loss of quality becoming too apparent?

I load on my website original files at 240 PPI, that are about 25 megs in size. (the website puts a 25mg limit on files) From them MPIX can make a pretty decent 18x24. I have the site set to hold orders until approved. If someone orders a larger size, I then send a file that is 300 PPI.

Originally Posted by mjp321

Thanks for all your replies!!! It's great having more experienced photographers on here to help us (you were shooting back in the 50's and I wasn't even born until the late 50's).

Your welcome Mike... Actually was shooting in the 30's my Mom gave me a broken bellows camera when I was seven. I took it apart and fixed it. (repaired many things from 5years on, thats another story.) Within a month my aunt taught me to process film, prints and to mix my own chemicals. By 1941 was selling photos of fires to the Boston Globe and Record. My Dad was in the Fire Dept, so I got to hang out at the station. When a second alarm came in, Id jump on my bike and head for the fire. Usually staff photogs had to fight Boston traffic and drive some distance. By the time they got there, the best ops for pictures were gone.

You can learn a LOT without going to school from reading and have read an average of four books a week.
Learned to read before I went to Kindergarten and read Huckleberry Finn by time I was six.
Going to school just certifies what you do know. If you run your own business you dont need it.

[mjp321]

Originally Posted by RJohnston

There is a difference between lying and ignorance.


It is not "new" technology, actually has been around for a long time. JPGs by their very nature are compressed. When you create a JPG from a RAW or TIFF image, it gets reduced in size according to how you set it. The greater the compression, the greater the loss of quality. But, some images depending on several things will compress a lot without loss and others will not compress as much. Like a clear blue sky will compress a lot more than one with lots of clouds, etc... When you open it, the computer reads the commands in the file and virtually reconstructs the pixels again.

Thanks for the reply and the information about your younger days - basically becoming a photojournalist when you were a kid! Cool!!! Thanks also about letting me know that you set the ppi in ACR or Lightroom. That's kind of what I thought was happening. I must have set the resolution to 240ppi in ACR.

By the way, I know that jpegs are compressed files, but I've never heard about any technology that would allow you to put 2 CDs worth of jpegs onto less than one CD. I opened the CD that Mpix gave me and right-clicked on one of the files and went to properties and it shows the jpeg is 2 MB in size. There's no way I can open that same file in Photoshop and somehow have the file size magically expand to 6.39MB is there? It's not a zipped file or anything. Even with zipped files, you don't really save all that much. In fact, if I save a copy of that same image in Photoshop (in a separate directory) at Quality 12, I get an image with a file size of 4.4MB. I don't think there's any way these images could have been scanned to give a 6.39MB file size and yet this is exactly what Mpix advertises. When I call them on it, they come up with some crazy lie. I don't really think Mpix can claim ignorance. It should be their job to know their own business practices.

Thanks again for your time!!!

[RocketRick]

When MPIX scans your negatives, or when your digital camera records an image, you end up with an image file (in some format -- RAW, JPEG, TIFF, or other) with certain image dimensions. For my Olympus E-520 DSLR, the files are 3648 pixels by 2736 pixels, which is just shy of 10 "megapixels" in total. I have a choice of the camera saving my picture files in Olympus RAW Format (as .ORF files) or as files compressed using the standard devised by the Joint Photographic Experts Group (JPEG).

The .ORF files record 16 bits each of red, green, and blue color data per pixel (subject to some caveats due to the way the actual sensors are laid out), and the .JPG files record 8 bits per color (RGB) per pixel. Let's ignore the ORFs for now, and just talk about .JPG files.

8 bits is a byte, and there are three colors per pixel (RGB), so it's three bytes of color data per pixel. 10 megapixels of data with 3 bytes per pixel means a total of 30 megabytes of data per .JPG file.

However, the actual .JPG files I get don't measure 30 MB in size; they average around 5 MB each, which is only one-sixth the size, even when I use the "super high quality" setting on my camera! Why is this?

The answer is simple: JPEG specifies a data compression method that reduces the file sizes significantly for photos. It's a "lossy" compression method, in that it actually changes some of the data to make the ultimate file size smaller, but it's designed with photographs in mind, so the changes that the compression method makes tend to be virtually unnoticeable at all but the highest compression levels for most images.

MPIX is sending you .JPG files that contain the same amount of image data (pixels with 24 bits total of color data each) that they told you, but because of the data compression, the actual file size needed to store that data is significantly reduced. They are not cheating you. (Comparing .JPG to .ZIP files is a red herring; the Lempel-Zev compression algorithm used by .ZIP files is lossless, and can't acheive anywhere near the same compression levels that the lossy compression method used by .JPG files is able to.)

Hope this helps!

- Rick

[RocketRick]

Regarding DPI, PPI, print dimensions and pixel dimensions:

First thing to clear up is a bit of terminology abuse. DPI means "dots per inch", and PPI means "pixels per inch". A "pixel" is the smallest "picture element" that can have a certain color value recorded in a data file. "Dots" are the physical things (like ink spots or glowing phosphors on a monitor screen) that are used to represent the pixels when they are printed or displayed.

If you're looking at an image on screen, the odds are *very* good that the two terms (DPI and PPI) are essentially interchangeable, as your monitor is likely to use a single glowing dot to represent each single pixel in any image displayed. However, print technologies vary somewhat, and a printer my use half a dozen different ink dots to recreate a single pixel, which is where some of the confusion arises.

Image data files (.JPG or otherwise) have certain pixel dimensions. My camera, as mentioned in my previous post, records 3648 pixel x 2736 pixel image files.

Most computer monitors from a few years back displayed approximately 72 DPI (and 72 PPI). This meant that, for instance, a roughly 17" diagonal screen (about 14 1/4" wide and 10 3/4" high) could display an image using 1024 dots by 768 dots. Modern monitors tend to be around 100 DPI/100 PPI, but it varies, of course.

Photos printed out (either by an inkjet printer or by WalMart, MPIX, CostCo, or your favorite photo processor) are usually done at 200 PPI or higher, so that the individual pixels making up the image are too small to be noticeable. 240 PPI is a commonly-used value. Without knowing the details of the exact technology used to print them, it's hard to say what DPI they use, other than to say that it's probably at least as high as their recommended PPI level.

For the sake of convenience when talking to people who may not know or care about the technical difference, many people will just use "DPI" to refer to both concepts, as it's easier for a non-technical person to understand "dots" than "pixels". Don't sweat it too much.

My camera's image files, at 3648 x 2736 pixels, if printed at 240 PPI, would be 15.2"x11.4". The native "aspect ratio" of my camera's sensor is 4:3, since there are 4 pixels in one dimension for every 3 in the other. That means I can print images at any dimensions with the same aspect ratio without having to crop or stretch the image to fit. An 8"x6" or 16"x12" print would be no problem.

If I did print a photo at 8"x6", I'd have 456 PPI (since 3648/8=456, and 2736/6=456, as well). At 16"x12", I'd still have 228 PPI, which is also plenty for a great-quality print. In fact, since most people view larger photos from further away, I could probably make a 32"x24" print at 114 PPI and have it come out with sufficient quality for framing.

Photoshop and other image editing software will generally allow you to adjust your image size either by setting dimensions in inches and setting a DPI or PPI value, or by just setting the actual pixel dimensions. If you have an image with certain pixel dimensions, and adjust just the DPI or PPI value, the software will generally show the image "shrinking" or "growing" in terms of inches, but this isn't actually a modification of the number of pixels, it's just changing their density.

When it comes time to send a file to be printed, the only thing that *really* matters is having sufficient pixels to be able to create a print at the size you want with a high enough PPI to look good. As an example, for an 8"x10" print at 240 PPI, you'd need your image to be at least 1920 pixels x 2400 pixels. (8 x 240 = 1920, 10 x 240 = 2400)

Hope this helps!

- Rick

[RJohnston]

Originally Posted by RocketRick

If you're looking at an image on screen, the odds are *very* good that the two terms (DPI and PPI) are essentially interchangeable, as your monitor is likely to use a single glowing dot to represent each single pixel in any image displayed.

This creates even more confusion. . . ..
If you are using an IBM PC, and go to "Display Settings" you will see that a Monitor actually uses Pixels.
My Monitor for example is set for 1680 x 1050 pixels...

[RJohnston]

Pixels are what your camera records the image in...

Dots per inch, is what a PRINTER uses and they are not interchangeable. On a screen 72 "pixels per inch looks good."

Printing an image, the "printer" is set to Dots per inch and it takes many dots to represent all the colors that make up that pixel, to print one pixel.

Generally most commercial printers want 240 minimum pixels per inch RESOLUTION to make a print with good resolution. Then they will print it at 300 DOTS per inch. HOWEVER, if you use a good printer at home, you can print at a _higher_ level of Dots per inch, producing a print which looks _better_ than those from commercial printers. They use 300 dots per inch to save ink, reducing the cost of the prints they produce, claiming that produces "satisfactory results."

"Custom Printers or Printing" produces better prints, because they use more ink.

Personally I only use 300 DPI to make wallet size to 5x7 inches. Generally print nothing less than 1200 Dots Per Inch when making prints 8x10 or larger. Most printers will print over 300 DPI, try it sometime and see the difference.

Have printed as high as 2400 Dots Per Inch, for Photography competitions. Most every time that I use 2400, tThe difference in quality in larger display prints, is well worth the extra ink used. Gives an "edge" in competitions when everything else, composition, subject matter, etc, is equal.

My printer will print at 4800 Dots per inch, but most times feel the cost/benefit ratio is not worth the additional ink. But, have used it a few times to produce some very dramatic blazing sunsets.