Scaling % value shown for imported graphics is not as expected

Things are making more sense now. Thanks a lot to you and Art for all the info!

Adrian

Adrian,

You are missing nothing, except that I would word it a little differently.

Image QUALITY has nothing to do with the dpi. It really has more to do with the total number of pixels in the image. People in the preprint business of scanning and retouching images often talk about the total number of pixels across the image's width and height rather than the dpi. The dpi setting has to do with the size of the image when it is printed; however, the dpi of a printed image may NOT be the same as the dpi setting stored with the image. In your case, your 96 dpi image is the SAME as your 300 dpi image because the two have the same number of pixels and each pair of corresponding pixels have the same values of RGB or CMYK. When you imported the 96 dpi image at 300 dpi, you are telling Frame to SCALE the image on the page so that its resolution is 300 dpi. When you imported the 300 dpi image, you told Frame to display it as is, that is, at its stored resolution of 300 dpi. Hence, Frame displays both images the same, because you have told it to. The quality of the two images is the same, because they have the same number of pixels.

If you had imported the 96 dpi image at 96 dpi, Frame would have printed at a larger PHYSICAL size than the 300 dpi image; BUT the two images would have the same quality; the 96 dpi image would not appear fuzzier than the 300 dpi image. Furthermore, if you had imported the 96 dpi image at 600 dpi, it would be printed at half the size of the 300 dpi image, had the SAME quality as the 300 dpi image, would not be fuzzier than the 300 dpi image, but would be harder to see because of the acuity of the human visual system. Thus, there is a limit to how high an image's resolution should be.

When Art suggests not lowering the resolution of your images, he is referring to two images at the same physical size but different dpi. That is, a 3 by 4 inch image at 96 dpi is fuzzier than the SAME 3 by 4 inch image at 300 dpi, because the two images have different number of pixels. Think of setting up a camera at a fixed place to take a picture. You take two pictures: one at 96 dpi and a second one at 300 dpi. They both capture the same content (say two trees and a house), at the same physical size, but at different resolutions.

In your case, I would not worry about the dpi setting stored in the image. Just import it into Frame and scale it there by percentage or by setting the dpi, which is the dpi of the printed image, not that stored within the image file. The image quality will not change during the import, no matter what the dpi setting or the Frame scaling is.

Van

Hi Art,

Here's a test I did...

I take a graphic that has a resolution to 96 dpi. I make a copy and set the resolution of that copy to 300 dpi in SnagIt. I import both copies into Frame. When importing the "96 dpi graphic" I choose to import it at 300 dpi. When importing the "300 dpi graphic" I leave the dpi setting as 300 dpi. Now I print the Frame document. Both graphics appear identical on the printout despite one graphic file having a lower resolution set for it.

From these observations I deduce that the resolution of a graphic file is simply a way to tell the program what size it should print at by default (though you can change this) and that having a higher resolution set for the file does not mean that the final printed graphic is really any better quality. As I said before and Van confirmed changing the DPI of a graphic does not change the actual pixels, so the behavior I am now seeing in this print test is actually what I would expect. What am I missing?

Adrian

Adrian,

Before you knock the resolution down, you should make sure that no one will ever want to print your output... for example, a customer printing a PDF who may not be happy with fuzzed out graphics.

Just a heads-up; it's better to keep your original in high res and knock it down for other purposes than to knock down your originals to the lowest common denominator and not be able to go back up.

Art

Thanks Van.

From what you are telling me it seems that my assumption that the dpi set for a graphic is really just for the purposes of printing rather than display is not correct. Everything I expected to see happening followed from that assumption. I would not even have noticed any of this had it not been for accidentally setting a DPI on my graphics files other than the 96 dpi they normally get stamped with. As I have absolutely no reason to set my graphic files to 200dpi I will change them back to 96dpi. In this way I know that after importing to Frame if I later resize a graphic I can just enter 100% to get it back to what it looked like when first imported.

Thanks for taking the time to explain things.

Cheers,

Adrian

Adrian,

1. In general, changing the dpi does NOT change the pixels inside the graphic; however, sophisticated programs (Photoshop) CAN also change the pixels when changing the dpi (this is called resampling). So, you have to be a little careful when changing the dpi to make sure you are not also resampling. A good check is the file size; changing the dpi without resampling should not change the file size.

2. As a simple test, I created a jpeg at a weird dpi (162), which corresponded to a physical width of 2 inches. I also saved the jpeg in the gif format. When I imported both images into Frame, the dialog box opened with the correct custom dpi of 162. In both cases, when I opened the properties dialog box, each image had a width of 2 inches.

When I imported both images into a blank Word document, the jpeg was displayed correctly at 2 inches wide; the gif was displayed at a slightly larger size, which corresponded to 96 dpi. Thus, in the case of gif files, Word ignores their dpi settings (I think this is due to the fact that the original gif specification did not allow a dpi setting; Word just sticks to that old specification).

3. I opened both in IE and each displayed at the same size; HOWEVER, I would not rely upon a Web browser, such as IE, as an arbiter of anything about image sizes. Use an image editor instead.

So, the main point of all of the above is that there is no guarantee that every application will display each image at its correct physical size based upon its dpi setting (see the Word example above). So long as the application you are using is getting it right, then there is nothing to worry about.

Again, if not clear, let me know,
Van

Thanks Van,

I have a graphic file set with a resolution setting of 200dpi. I made a copy and set the resolution to 96dpi using SnagIt. Then I opened them both up in various programs IE, Picture Viewer, SnagIT, PaintShop. In all these programs, the graphics display identically on screen at a view size of 100%. This is what I would expect as my (probably flawed) understanding is that the dpi setting of a graphic file is really intended as a default for printing and not for on-screen display. (Changing the resolution does not change the pixel info inside the graphic file in any way, right?) In contrast with IE, PaintShop and SnagIt, if I open the two graphics in Word or Frame they appear at different sizes on the page. Frame and Word are taking into account the dpi setting of the graphic in order to display it while other programs are not. (You suggested the test of importing at 200dpi and checking the width and height. When I do this the graphic appears much smaller in Frame than it does when opened in IE at 100%.)

Basically, if I take a screenshot of a GUI window and at some later stage in the life of that screenshot I see a field called Percent my expectation is that entering 100% will give me a screenshot that appears exactly like the original GUI window did, but this does not happen. In other words, I would expect any dpi setting the graphic file had to be ignored.

Not sure if I am explaining this very well

Adrian,

I believe you are confusing a few things. When you import a bitmapped image and CHANGE the dpi to something other than that of the bitmap, you are indeed scaling the image, hence the 208%. Changing the dpi in Frame is not the same as changing the dpi in an image editing program. Setting the dpi in Frame tells Frame to scale the image so that it displays at X dpi in the Frame document; thus, a 200 dpi image set at 96 dpi is scaled by 208% to display at 96 dpi. So, Frame is behaving as it should.

You can also import at 200 dpi, then check the object properties of the image. It should have the same width and height (in inches, say) as it does in IE or other image editing program.

You also said, "After import the graphic looks the same in Frame as when opened in IE or any graphics program and viewing at 100%."

What do you mean be "looks the same as"? If you mean each pixel in the original is there in Frame, then everything is OK. If you mean the physical dimensions (say, width and height in inches) are the same, then that is probably meaningless, because 100% in Frame and 100% in IE may not mean the same thing, that is, the two programs may not display the image with the same PHYSICAL dimensions on the screen.

Hope this clears things up. If not, maybe I am misunderstanding what you are saying.

Van

version 7.2b144

What specific version of FM (from Help > About, the "pxxx" numbers)?