HELP: PS 6.01 72 VS 300 DPI Dilemma

Ok, I know this issue has already been hashed here but I am still at a loss of why things are happening.

Scenario:

1). Open 1MB JPEG in Photoshop 6.0 / 300 DPI / shot in CoolPix 995 "fine" mode / 2560 x 1920
2). Apply auto-levels and unsharp-mask
3). Save file, JPEG at it's 10 setting (high quality), no resize / 2560 x 1920

When checking the EXIF info, the file now is 72 DPI but still at 2560 x 1920. What's happening here. Is Photoshop making a mistake in the DPI? Even more odd, if I change the size to 300 DPI within PS, the file print size goes smaller instead of larger.

If the dimensions are the same 2560 x 1920, does it matter what the DPI is? I'm left wondering why PS took it to 72 DPI from 300 DPI with no loss of file size.

HELP!

My understanding is that the 72 dpi you're seeing doesn't mean your file has shrunk or you lost data. As the physical dimensions (height/width) increase, the dpi decreases, and visa versa. The SIZE of the file remains unchanged; you lose no data. This is a common question I notice reappearing from time to time. For printing, you would click "off" resample and adjust the physical dimensions to the print size you want. That 72 dpi will go up as you reduce the print size from 20"x20" to 4"x6" or whatever.

Good Day

RPK said:

Ok, I know this issue has already been hashed here but I am still
at a loss of why things are happening.

Scenario:
1). Open 1MB JPEG in Photoshop 6.0 / 300 DPI / shot in CoolPix 995
"fine" mode / 2560 x 1920
2). Apply auto-levels and unsharp-mask
3). Save file, JPEG at it's 10 setting (high quality), no resize /
2560 x 1920

When checking the EXIF info, the file now is 72 DPI but still at
2560 x 1920. What's happening here. Is Photoshop making a mistake
in the DPI? Even more odd, if I change the size to 300 DPI within
PS, the file print size goes smaller instead of larger.

If the dimensions are the same 2560 x 1920, does it matter what the
DPI is? I'm left wondering why PS took it to 72 DPI from 300 DPI
with no loss of file size.

HELP!

Click to expand...

That makes sense.

BTW, how are you able to get 2560x1920 with a CP995? That's the highest resolution I can get with my CP5000.

With 2560x1920 pixels coming from the camera,

at 72 DPI your image measures 35.56 in. x 26.67 in.
at 300 DPI it will measure 8.53 in. x 6.4 in.

both will produce a 14.4 Mb file (uncompressed)

Using Photoshop to get a desired print size, like 7 in. x 5 in., I usually adjust the physical size to match one of the dimensions to either 5 in. or 7 in. Then I raise the PPI resolution until the filesize is near the original 14.4 Mb.

Then I crop the image to get the other dimension to exactly 7 in. or 5 in.

Using this method, am I compromizing the image quality by going through Photoshop's bicubic interpolation? Would I be better off using the more advanced interpolation algorithms in Qimage Pro? However, you don't have the ability to control the exact crop direction with Qimage.

Kevin said:

Good Day

RPK said:

Ok, I know this issue has already been hashed here but I am still
at a loss of why things are happening.

Scenario:
1). Open 1MB JPEG in Photoshop 6.0 / 300 DPI / shot in CoolPix 995
"fine" mode / 2560 x 1920
2). Apply auto-levels and unsharp-mask
3). Save file, JPEG at it's 10 setting (high quality), no resize /
2560 x 1920

When checking the EXIF info, the file now is 72 DPI but still at
2560 x 1920. What's happening here. Is Photoshop making a mistake
in the DPI? Even more odd, if I change the size to 300 DPI within
PS, the file print size goes smaller instead of larger.

If the dimensions are the same 2560 x 1920, does it matter what the
DPI is? I'm left wondering why PS took it to 72 DPI from 300 DPI
with no loss of file size.

HELP!

Click to expand...

Click to expand...

Ok, I may be off on the dimensions.

What I'm asking is why PS is dropping / changing the original file of 300 DPI to 72 DPI. I cannot locate anything that would drop / change the file.

I would like PS to keep it where it is, 300 DPI right off the camera. Just editing the image (levels) should not reduce the image by 228 DPI. No cropping has been done.

Even if I just open then save as, the file drops to 72 DPI.

RPK said:

Ok, I may be off on the dimensions.

What I'm asking is why PS is dropping / changing the original file
of 300 DPI to 72 DPI. I cannot locate anything that would drop /
change the file.

I would like PS to keep it where it is, 300 DPI right off the
camera. Just editing the image (levels) should not reduce the image
by 228 DPI. No cropping has been done.

Even if I just open then save as, the file drops to 72 DPI.

Click to expand...

Hopefully this helps somebody: In photoshop after you open up an image from your camera and then you click on Image Size, your photo will be at 72ppi with a 14.1MB file and the image size is 35.556 x 26.667. Here is a suggestion: Disable Resample Image and type in the width and height that you want and you will notice the file size stays the same but your res goes up to 365.714 ppi which means that you do not losing any detail in the image.
Just a suggestion
Andrew

Andrew Curatola said:

RPK said:

Ok, I may be off on the dimensions.

What I'm asking is why PS is dropping / changing the original file
of 300 DPI to 72 DPI. I cannot locate anything that would drop /
change the file.

I would like PS to keep it where it is, 300 DPI right off the
camera. Just editing the image (levels) should not reduce the image
by 228 DPI. No cropping has been done.

Even if I just open then save as, the file drops to 72 DPI.

Click to expand...

Hopefully this helps somebody: In photoshop after you open up an
image from your camera and then you click on Image Size, your photo
will be at 72ppi with a 14.1MB file and the image size is 35.556 x
26.667. Here is a suggestion: Disable Resample Image and type in
the width and height that you want and you will notice the file
size stays the same but your res goes up to 365.714 ppi which means
that you do not losing any detail in the image.
Just a suggestion
Andrew

Click to expand...

Forgot to mention I typed in a 7 x 5 for width & height
Sorry 'bout dat
Andrew

PIXEL COUNT is what makes up an image size. You pixel count has not changed.

DOTS PER INCH is simply a setting for printing/displaying the image. Therefore, an image at 600 X 600 printed at 300 dpi will yield a 2 X 2 print. Printed at 200 dpi, a 3 X 3 print will result, but with LESS DOTS IN EVERY INCH printed, therefore making it look different (lower quality). DPI is simply the file's setting for how you want it to print. Both files in the above example have the EXACT same digital information, they just print/display differently (most displays are 72 dpi, so the video card converts anyway).

Hope this clears your worries.

Geoff Thompson
http://www.fotki.com/geofft/

I really think I am missing something here.

Plain and simple ... please!

Why is Photoshop changing the image from 300DPI to 72 DPI just by saving it? No modification, no resize, nothing done at all. Open, save as and it's changed.

What can I do to keep it at it's original DPI, no alterations?

Feel free to bonk me on the head if I'm not getting it.

Anyone ???

RPK said:

I really think I am missing something here.

Plain and simple ... please!
Why is Photoshop changing the image from 300DPI to 72 DPI just by
saving it? No modification, no resize, nothing done at all. Open,
save as and it's changed.

What can I do to keep it at it's original DPI, no alterations?

Feel free to bonk me on the head if I'm not getting it.

Click to expand...

RPK said:

RPK said:

I really think I am missing something here.

Plain and simple ... please!
Why is Photoshop changing the image from 300DPI to 72 DPI just by
saving it? No modification, no resize, nothing done at all. Open,
save as and it's changed.

What can I do to keep it at it's original DPI, no alterations?

Feel free to bonk me on the head if I'm not getting it.

Click to expand...

Click to expand...

I think what everyone that posted to your question is saying is your image IS shot at 300 DPI. But you probably shot it in UXGA, SXGA, etc., but not in FULL, which mean the image is saved as a .JPG, not .TIFF. Whenever it is saved in .JPG, it is compressed to be viewed on a screen resolution of 72 DPI. Again, that is being VIEWED at 72 DPI, since that's all the computer screen needs. That is the camera's compression. All 300 DPI is there, it is just compressed for the screen. If you shot in FULL, the camera does no compression, that is why the file size is like 9 MB, because nothing changes...it is FULL.

If you open your image in Photoshop and select "Image Size," you will see it is at 72 DPI. Make sure the "Resample Image" is unchecked. Now, if you type in the dimensions you want your image to print, you will see the resolution change to 200-300, etc. for printing.

I was confused like you, but I'm beginning to understand. Hope this helps.

RPK said:

RPK said:

I really think I am missing something here.

Plain and simple ... please!
Why is Photoshop changing the image from 300DPI to 72 DPI just by
saving it? No modification, no resize, nothing done at all. Open,
save as and it's changed.

What can I do to keep it at it's original DPI, no alterations?

Feel free to bonk me on the head if I'm not getting it.

Click to expand...

Click to expand...

Also, in Photoshop, it is always best to save as .TIFF, not .JPG.

Hi,
Pshop DEFAULTS to 72 dpi
your pic would be 70 50 cm at that
change the dpi to 300 and walla...10 by 8 approx
UNCHECK RESAMPLE when you do this
good luck

chilly

RPK said:

Ok, I know this issue has already been hashed here but I am still
at a loss of why things are happening.

Scenario:
1). Open 1MB JPEG in Photoshop 6.0 / 300 DPI / shot in CoolPix 995
"fine" mode / 2560 x 1920
2). Apply auto-levels and unsharp-mask
3). Save file, JPEG at it's 10 setting (high quality), no resize /
2560 x 1920

When checking the EXIF info, the file now is 72 DPI but still at
2560 x 1920. What's happening here. Is Photoshop making a mistake
in the DPI? Even more odd, if I change the size to 300 DPI within
PS, the file print size goes smaller instead of larger.

If the dimensions are the same 2560 x 1920, does it matter what the
DPI is? I'm left wondering why PS took it to 72 DPI from 300 DPI
with no loss of file size.

HELP!

Click to expand...

The PROBLEM is that your 1MB file was always 72PPI to begin with, NOT 300PPI! Just open the original file in photoshop and go to Image Size....see its always been 72PPI from the start. That's the resolution your JPEG's are created IN the camera. TIFF's are created @ 300PPI in the camera, albeit as much smaller inches dimension. CHECK YOUR FILES in Photoshop before changing anything, and this will end the confusion.

ps NEVER resave a JPEG as a JPEG unless its for the web or you don't care about maintaining image quality...everytime JPEG is applied alot of pixels are

discarded. The industry standard for archiving final files is the lossless TIFF format.

I think you are getting confused by the way Photoshop uses the term resolution.

If you have a 2560x1920 pixel image with a resolution of 300 pixels/inch it will produce a print that is 8.54" x 6.4"

2560 / 300 = 8.54" x 1920 / 300 = 6.4"

If you have a 2560x1920 pixel image with a resolution of 72 pixels/inch will produce a print that is 35.55" x 26.66"

2560 / 72 = 35.55" x 1920 / 72 = 26.66"

Both settings are recording the same number of pixels. One is putting it into a smaller space. They both produce the same size file because they both have 2560x1920 pixels. Photoshop (according to another post) just defaults to 72 DPI, but it still retains the same pixel image size. The only thing that changes is the document size. Maybe we should find some way to change Photoshop to always retain the 300 DPI setting.

RPK said:

I really think I am missing something here.

Plain and simple ... please!
Why is Photoshop changing the image from 300DPI to 72 DPI just by
saving it? No modification, no resize, nothing done at all. Open,
save as and it's changed.

What can I do to keep it at it's original DPI, no alterations?

Feel free to bonk me on the head if I'm not getting it.

Click to expand...

If you are using compression on your camera, it produces a jpeg. Then open in Photoshop for editing and then 'SAVE AS...' a jpeg and use a new name. The new file is further compressed and the original JPEG is unchanged. So, you have your originally 1.5 Mb file instead of a 14.4 Mb TIFF. Why take up the additional 12.9 Mb when you don't have to???

Are you suggesting the edited file should always be saved as a TIFF?

I've heard many people say that saving it using the 'Save for web' method allows greater control over the compression setting and provides side by side views of the uncompressed and compressed files so you can see the effects the compression will have on image quality. With this you should still be able to save using jpeg and judge how it will effect the final quality of the edited file.

Bruce M. said:

ps NEVER resave a JPEG as a JPEG unless its for the web or you
don't care about maintaining image quality...everytime JPEG is
applied alot of pixels are
discarded. The industry standard for archiving final files is the
lossless TIFF format.

Click to expand...

That is what I am getting at. I would prefer to retain the 300 DPI setting as the camera records it. DPI should not change just by opening and saving as another file name. No processing through Photoshop, saving it to another file.

As far as saving as a .TIFF. Since the original file was .JPG, what are the benefits (if any) of saving as .TIFF? The file size is larger and I won't gain any of the data lost from the camera saving as a .JPG in the first place.

Thoughts?

noreltny said:

Both settings are recording the same number of pixels. One is
putting it into a smaller space. They both produce the same size
file because they both have 2560x1920 pixels. Photoshop (according
to another post) just defaults to 72 DPI, but it still retains the
same pixel image size. The only thing that changes is the document
size. Maybe we should find some way to change Photoshop to always
retain the 300 DPI setting.

Click to expand...

I don't know why Photoshop does that but anything you open for the first time in photoshop (jpeg) it puts it to 72. The first thing I always do is image size MAKE SURE YOU TURN RESAMPLE OFF! and put it back to 300 for printing. try checking out http://www.communityzero.com/PUG website out. It's a photoshop users group with lots of nice people in it.

RPK said:

Ok, I know this issue has already been hashed here but I am still
at a loss of why things are happening.

Scenario:
1). Open 1MB JPEG in Photoshop 6.0 / 300 DPI / shot in CoolPix 995
"fine" mode / 2560 x 1920
2). Apply auto-levels and unsharp-mask
3). Save file, JPEG at it's 10 setting (high quality), no resize /
2560 x 1920

When checking the EXIF info, the file now is 72 DPI but still at
2560 x 1920. What's happening here. Is Photoshop making a mistake
in the DPI? Even more odd, if I change the size to 300 DPI within
PS, the file print size goes smaller instead of larger.

If the dimensions are the same 2560 x 1920, does it matter what the
DPI is? I'm left wondering why PS took it to 72 DPI from 300 DPI
with no loss of file size.

HELP!

Click to expand...

--Debbie

Just to clarify my original posting.

Per the EXIF data on a raw and unedited JPG straight out of the camera, the DPI setting show as 300 DPI. Only after "saving as" through Photoshop does it drop down to 72 DPI. No actions, crops or edits were done, just simply saving it as a different file.

I'm very lost ...

Either the camera is mis-reporting the DPI as 300 or Photoshop is doing something that I don't know about.

When saving the "edited" .JPG, I always choose the lowest compression / highest file size method. This leads to another question.

If my original .JPG is say 1.MB and I save in PS with a compression setting of 12 (highest I believe) what's happening to inflate the file upwards to 2.0MB? I am not gaining data, I believe it's just compressed less. With this in mind, should I always save at "12" and have a larger file than the original or go for the normal compression setting?

Now on to saving as a .TIFF from a .JPEG, what is the point there. If it's already compressed once, didn't I loose the data? Will I have any additional gain by using the .TIFF format. Bear in mind, the file was a .JPG in the first place.

Debbie, that's exactly what I am talking about. Thank you for seeing through the haze.

Debbie said:

I don't know why Photoshop does that but anything you open for the
first time in photoshop (jpeg) it puts it to 72. The first thing I
always do is image size MAKE SURE YOU TURN RESAMPLE OFF! and put it
back to 300 for printing. try checking out
http://www.communityzero.com/PUG website out. It's a photoshop users
group with lots of nice people in it.

Click to expand...

RPK said:

Debbie said:

I don't know why Photoshop does that but anything you open for the
first time in photoshop (jpeg) it puts it to 72. The first thing I
always do is image size MAKE SURE YOU TURN RESAMPLE OFF! and put it
back to 300 for printing. try checking out
http://www.communityzero.com/PUG website out. It's a photoshop users
group with lots of nice people in it.

Click to expand...

Click to expand...

Look, it's just a matter of interpretation and a bit of confusion. Your camera is telling you it is 300DPI because that's the amount of data it captured. But if you select any size like UXGA, SXGA, etc., other than the FULL size, it will transfer onto your computer at 72 DPI size, but all 300 DPI is there when you need to bring it to size for printing.

Follow this example. Take a picture and upload the .JPG image and open with Photoshop. Look at the image size and resolution. It will say 72 DPI. Now, make sure the "resample" is unchecked in Photoshop and type in the size you want to print, say 8"X10," and look at the reslotution now. It will change.

Here's where you are getting confused. When you upload the image onto you computer, they (the camera and Photoshop) assume you want to see it fit on your screen, thus 72 DPI. They resized it, but retain all data until you resample it...that is why everyone says to make sure the "unsample" is unchecked.

Now take an image in FULL and the camera will save it as a .TIFF. Open that in Photoshop and see how huge it is. Look at the resolutiion, it will be 300 DPI, since there is no compression at all. That is the difference. If .TIFF, nothing changes, all data is there. In .JPG, it gets resized to save space, bua all data is there when the time needs it to be that full size.

Hope this helps,
Tsan