Size and quality question

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Dale_tem

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Dale
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If I have a 3000 x 3000 pixel image and I print it at 300dpi it will be 10 inches square.

Lets say I want to make the image approx 8" square. What would be the best way to do it?

Reduce the number of pixels to 2400 x 2400 (resample) and print at 300dpi

OR

Change the dpi to 375 dpi and not resample the image (image is still 3000 x 3000).

Logically I think I should change the dpi as I'm not editing the image. I'm not trying to make what fitted in 10 pixels now fit in 8 pixels. Which would give the better quality.

Another question - what DPI is relistically the minimum when printing? If I was printing out an A3 print to hang on the wall, what is the minimum resolution I could get away with? Is higher DPI better or is there a point where higher doesn't actually improve anything?
 
Don't confuse Dots per Inch, with Pixels per Inch. Dots refer to the print making process whilst pixels are image based. They are not the same. In your case I wouldn't do anything. The printer software will happily take you 3Kx3K pixel image and pass it to the printer so that it can print the required size.

The printer software takes the image and re sizes it to the appropriate DPI for the printer to handle. I have images that were taken with a Canon 300D several years ago ( 6 Mp camera). I have beautifully sharp photographic prints from these images that are 20" x 30" in size. It's all down to how the images are handled and what software is used in both the processing and printing.

Don't get too hung up on DPI. it really only comes into play at the output stage of the printing process, when the data is being sent to the printer.
 
But If I print an image and it comes out at 10" square and I only want it 8" squared, I would need to change the size in photoshop. So what is the best way of doing it?
 
I think I now understand what you want to do. You have an image that is currently 10" sq with a resolution of 300 dpi. Now you want to print this on say an A4 sheet of paper but want the image to be 8" sq.

I think either method would work. Would you see a difference in image quality on a print that size if you increased the dpi, I don't think you would. My personal approach would be to keep the dpi the same and change the dimensions, just to keep things as "Standard" as possible. But as i said either would work satisfactorily. In theory increasing the resolution should give the better quality, there is a whole printer pipeline involved with the final output which would affect the final print. For example if you resized using the higher dpi, and then printed the image using 300dpi as the printer resolution, any gains would have been eliminated. Plus of course what effect the printer software would have may also have a bearing on the quality of the final output
 
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1. Click the crop tool.
2. In the toolbar type, width 8in, height 8in dpi 300
3. Crop the image

Wherever you crop on the image it will resample to 8"x8"
 
I am trying to enquire if it should be resampled or not.

If I change the doing the original image remains the same, it prints smaller. No loss in quality.

If I resample to make it smaller would it not lose quality? I am losing detail as the detail in 3000 pixels is now squeeze d into 2400 pixels.
 
I'd suggest you change the ppi to 360, if your using an Epson printer this is a better res to go with than 300ppi.

If your adjusting it in the Image Size dialog box make sure Resample Image is unchecked.
 
Anyone else have any input on resampling vs changing dpi?
 
snapalot and whitey please read my question.

I know how to, I'm asking which is the best way and you have both majorly missed my point and added nothing to this thread :)
 
Increasing dpi should give you a higher quality image but I doubt there will be any difference between the 2.

If its an epson printer then make it 360 dpi and resize to 8x8.
 
I agree with Whitey & Snapalot, crop to 8x8" at 300dpi . Your question was "Lets say I want to make the image approx 8" square. What would be the best way to do it?"
If your existing file is 10x10" I am assuming that you have already cropped it (unless it's a scan from a 120 6x6 neg)
As long as you have saved your initial crop from your original file as a tiff no problems, just crop to 8x8 @300 as said.

You then said "But If I print an image and it comes out at 10" square and I only want it 8" squared, I would need to change the size in photoshop. So what is the best way of doing it?"
Once again crop to 8x8" at 300dpi.

Posted with good intention.

Joan
 
Have you investigated the other way or are you just saying how you normally do it?

Cropping the image means reducing the pixels and so reducing the quality.

Changing the DPI does not reduce quality.
 
It's how I would advise any of our customers, crop to the size print that is required.
 
I've been reading various bits of info...

One note is that after a digital photo has been resized, it will need to be re-sharpened.
Click to expand...

This is because you have modified the image and detail has been lost in the resampling.

Everyone seems to resample and have every image at 300dpi and this is just how it has been done, yet they are losing quality doing this.

Hi Dale - the quick answer is that there is no need to re-sample or change anything.

Depending on the software you are using - if Photoshop for instance you can print the photo exactly as is by simply choosing 8" square paper and "Scale to fit media" - Photoshop will print your 3000 x 3000 to 8" square (no need to worry about the dpi setting).

If you are using software that actually uses the dpi setting to set the print dimensions (and it can be done this way through Photoshop, but I prefer the faster/easier "scale to fit media") then your second option is the one to use - set the dpi to 375 without re-sampling the image.

Bottom line is that you don't want to re-sample the image - leave it at 3000 x 3000.

All the best,

Ken
Click to expand...

From the author of....

http://www.rideau-info.com/photos/mythdpi.html

So the answer would be to change the DPI to keep quality, but with photoshop you can get it to print at a set size.
 
snapalot and whitey please read my question.

I know how to, I'm asking which is the best way and you have both majorly missed my point and added nothing to this thread
Click to expand...

Lets say I want to make the image approx 8" square. What would be the best way to do it?
Click to expand...

You asked the best way, in ours, and others opinions this was the best way, if you aleady knew, why ask?
 
And how many pixels can you get to dance on the head of a pin?

All printing devices have a finite resolution - and sending a file that is larger will not make the image any better - and can, if you wish to be really anal, reduce the quality, as interpolation down can be as destructive to image quality as interpolation up. (but only if the file is way too big.
 
Dale - have you got Capture NX2? Here's the relevant section from the user manual.

The Resample Image option - enables you to change the file to match a specific output size and resolution. Enter the desired Width, Height, and Resolution, or pixel dimensions, and the image will be interpolated using a bi-cubic interpolation method. Image data is either created or discarded so that the image fits within the newly set parameters.

The Don't Resample Image option- enables you to redistribute the image information without changing image data. While in this mode, image detail cannot be either created or discarded. Entering either the new Width or Height or the new Resolution will automatically adjust the other set to match. For example, changing the height of an 8 inch by 10 inch image at 300 dpi to 4 inches will result in a 4 inch by 5 inch image at 600 dpi.

Hth.
 
Dale_d3100 said:
Cropping the image means reducing the pixels and so reducing the quality.

Changing the DPI does not reduce quality.
Click to expand...

Neither statement is true or false

300dpi was generally considered to be the point where any increase in resolution would not be noticeable to the human eye, hence why it is usually quoted as minimum required resolution. In reality you would be hard pushed to notice 240dpi or higher

These figures were pretty standard until printer manufacturers can up with variable sized dots and don't forget most Epson's have the ability to print at 1440dpi or 2880dpi so the printer driver is also interpolating

In reality it is the end result you should be considering and I very much doubt that you will see any difference.

Mike
 
snapalot said:
You asked the best way, in ours, and others opinions this was the best way, if you aleady knew, why ask?
Click to expand...

I don't know, but you all said crop without a reason why or why the other way is bad.


Thanks for the input everyone. My head said what the nx2 manual said, but most seem to resample and I wondered why.
 
mike weeks said:
Neither statement is true or false

300dpi was generally considered to be the point where any increase in resolution would not be noticeable to the human eye, hence why it is usually quoted as minimum required resolution. In reality you would be hard pushed to notice 240dpi or higher

These figures were pretty standard until printer manufacturers can up with variable sized dots and don't forget most Epson's have the ability to print at 1440dpi or 2880dpi so the printer driver is also interpolating

In reality it is the end result you should be considering and I very much doubt that you will see any difference.

Mike
Click to expand...

The 1440dpi or 2880dpi of the printer are not the same as the 300dpi and 240dpi you mentioned above.
The 300 and 240 figures should really be ppi as they are obtained by dividing pixels by inches giving pixels per inch or ppi. PPI tells you how many little squares there are in each inch of the "mosaic" which makes up the picture.
The 1440dpi or 2880dpi refer to actual drops of ink which the printer jets out, either 1440 drops per inch or 2880 drops per inch, each pixel can be made up of more that one drop of ink to produce accurate colours.
Therefore printing at 1440dpi or 2880dpi does not mean that the printer is interpolating pixels, just using more dots per pixel.
 
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The 300 and 240 figures should really be ppi as they are obtained by dividing pixels by inches giving pixels per inch or ppi.
Click to expand...

No, I am quite right as I am referring to printed image, the size of 300dpi is taken from printers screens as in traditional print shop printing and not domestic inkjet. I do know the difference between dpi and ppi hence why I have used correctly.

Therefore I am also correct when I mention the 1440 or 2880 of an inkjet as a calculation has to be carried out between the resolution of the electronically stored image and how this will be printed - the common term for this change of resolution is interpolation

ppi is pixels per inch, with pixel being a made up word from picture elements and is usually accepted as an electronic display measurement.
 
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