Rick... You are very correct about my brashness. My apologies to all of you. I was anxious to try and squelch some misconceptions and got carried away. David Creamer was particularly incensed with me because he thought I was aiming the whole rant at him. This was not the case, of course, but I can see his point. in the meantime, he and I have called a truce, as we both have better things to do.
Dude... ****************************************** At 06:26 AM 2/6/2008, richard.melanson at us.tel.com wrote: >Dude, you may be the expert on this, and the info you supplied in >your response is so good I am saving it, but how about a little >respect for everyone on the list. I believe whatever anyone said in >an attempt to help they believed to be accurate and helpful. To say >and I quote you "Well, I've had enough of this nonsensical babble. >None of you seem to understand what you are talking about when it" >is a little strong. Life is too short, take a deep breath and enjoy!! >Rick > >-----Original Message----- >From: framers-bounces at lists.frameusers.com >[mailto:framers-bounces at lists.frameusers.com] On Behalf Of Dennis >Brunnenmeyer >Sent: Tuesday, February 05, 2008 2:37 PM >To: David Creamer; framers at lists.frameusers.com >Subject: RE: Working with Images > >Rant begins... > >Well, I've had enough of this nonsensical babble. None of you seem >to understand what you are talking about when it comes to dealing >with screenshots and raster images, (a.k.a. bitmapped images) as >opposed to vector or llne art. > >First of all, display devices, whether printers or monitors, have an >upper limit on their ability to resolve (print or display) image >detail, which by the way is what "resolution" is a measure >of...meaningful detail. The best my aging but faithful laser printer >can do is 600 dpi, while my uppity LCD monitor can display up to 100 >dpi, with its1600 x 1200 native resolution on an LCD panel that is >exactly 16" wide x 12" tall." You cannot see nor capture anything >and create a screenshot image with higher resolution than the >display device. You cannot print anything with higher resolution >than the printer can resolve. If you feed a high resolution image to >a medium resolution printer, it will interpolate (resample) the >image down to medium resolution quality. It has to, as it cannot put >all of that information on paper. If you take an very high >resolution (total pixel count) image of size 4000 x 3000 pixels (12 >megapixels) and display the full image it on a monitor like mine, you will >not see all of detail in the image and hence you will not be able to >capture all of the detail in a screenshot. > >Most of you seem to appreciate this, but some of you think you can >improve resolution by artificial means. No, you cannot. > >A true measure of the resolution of an image is the original size of >the image in total pixels, assuming it is true to begin with. That >is, assuming a perfect digital camera with a perfect lens and the >ability to produce a "raw" bitmap (rather than a compressed JPEG >file), that 12 megapixel CCD image sensor will produce a significant >improvement in the resulting image over a 2 megapixel CCD sensor. >That image quality is NOT described by either ppi or dpi. It is a >function of the number of pixels in the X direction and the number >of pixels in the Y direction. > >Now the plot thickens when I return to the subject of screenshots, >because if I run my graphics card at 1600 x 1200, the type, icons >and dialog boxes are uncomfortably small for me to read on the >monitor, so I set the graphics card to display its images at 1280 x 960 dpi. >At this point, the maximum image size that can be displayed without >loss of resolution is now 80 ppi. That's 1280 divided by 16. >[Unfortunately, since the graphics card's resolution doesn't match >the native resolution of the LCD panel, the on-screen picture is not >as crisp as it could be. This is a result of "aliasing" artifacts, >but that's a topic for a different thread.] > >Note that in the above paragraph, I switched from dpi for display >devices to ppi when describing image size. This is a meature of the >physical size of a digital image (as printed or displayed) and >should be described in ppi. The ability of a device to display or >print an image should be described in dpi, or alternatively, lpi for >lines per inch, or pixel spacing, as in 0.25mm. There is a tendency >to intermix this terminology and hence confuse the issues you are discussing. > >Now that I have set my graphics card to 1280 x 960 for this monitor, >the maximum resolution of any image I capture from the screen is 80 >ppi, regardless of whether I capture a whole screen or just a region >of it. If I set the "resolution" of the screen capture program >(Snag-It or HyperSnap) to 80 ppi, then the resulting image will be >the same physical size as it appeared on the screen, 100%. If I set >the capture "resolution" to 160 ppi, then the image will be half the >physical size as it appeared on the screen, BUT IT WILL HAVE EXACTLY >THE SAME NUMBER OF PIXELS. The resolution has not be improved, as no >more detail has been added. > >Upsampling and/or downsampling using any kind of pixel resampling >(a.k.a. interpolation), whether bicubic or otherwise, ALWAYS removes >detail from the image. In either case, new pixels are created that >are some kind of average of the original ones. They're guesses at >what shoud be there at that point in the image, and not real >information that wasn't there before. No new detail nor image >improvement can be added by interpolation. > >Now, however, you can re-scale an image in programs like Photoshop >by keeping the same number of pixels (do not interpolate) and >altering the size of the image in the X and Y directions equally. >For example, if I took the 160 ppi screenshot described in the >previous paragraph and re-scaled it in Photoshop without resampling >the image, and if I prescribed a new size of 80 ppi, the resulting >image would grow back to 100% in size and have still have exactly >the same number of pixels as before. The resolving power of the >image has not changed, and no more detail has been provided. This is >a correct way to get an image to the size you want it in your >document. Another way is to import it as is and resize it in Frame >using the image's corner anchor points while holding the Shift key down. > >Don't mislead yourselves and others by thinking that the more >"resolution" in your screenshot capture application you use gives >you better results, and don't mislead yourselves by thinking you can >add more resolution by upsampling (or rescaling, for that matter) to >a different ppi or by adding more artificial pixels. > >Now, on another topic, there seems to be a rule of thumb that "most >SVGA screens are 96dpi." Someone came up with the statement that a >20" screen with a 1280 x 1024 display is, of course, 96 dpi. That's >utter nonsense. Given that screen size is measured on the diagonal, >and assuming the old standard 4:3 aspect ratio, a 20" screen is 16" >wide and 12" tall...rather like my Samsung LCDs. With 1280 pixels in >the X (horizontal) direction, the screen resolution is 80 dpi, not >96 dpi. Any way you manipulate the numbers, 96 dpi is not a result. >By the way, here I assumed a 4:3 aspect ratio, which is the ratio of >width to height. If I ran my graphics card at 1280 x 1024, circles >would be egg-shaped, since that resolution calls for a screen with a >5:4 aspect ratio. Of course, wide screens have a different aspect >ratio, but the principles are exactly the same. > >I have no idea what David meant by this statement: "Again, >referring to my last post, monitor resolution only counts if >capturing an entire screen." Monitor size DOES count if you're >trying to calculate the resolving power of your monitor in dpi and >hence the maximum resolution attainable in a screenshot. It's the >horizontal resolution of your graphics card setting divided by the >width of the display area in inches or centimeters, or in the example given, >1280/16 = 80 dpi. > >End of rant ... > >Flame away...but be sure you know what you are talking about and >quit misleading others if you don't understand this. > >Dennis Brunnenmeyer >*************************************************************************************** > > >At 09:09 AM 2/5/2008, David Creamer wrote: > > > How can SnagIt capture an image at a higher resolution than what the > > > screen is set to? A 20" screen at 1280 x 1024, for example, is 96 > > DPI. How do you > > > get 200 DPI out of that? > > > >Screen size (20") is meaningless, only the monitor resolution counts. > >Again, referring to my last post, monitor resolution only counts if > >capturing an entire screen. > >Dennis Brunnenmeyer >Director of Engineering >CEDAR RIDGE SYSTEMS >15019 Rattlesnake Road >Grass Valley, CA 95945-8710 >Office: (530) 477-9015 >Fax: (530) 477-9085 >Mobile: (530) 320-9025 >eMail: dennisb /at/ chronometrics /dot/ com >_______________________________________________ > > >You are currently subscribed to Framers as richard.melanson at us.tel.com. > >Send list messages to framers at lists.frameusers.com. > >To unsubscribe send a blank email to >framers-unsubscribe at lists.frameusers.com >or visit >http://lists.frameusers.com/mailman/options/framers/richard.melanson%40us.tel.com > >Send administrative questions to listadmin at frameusers.com. Visit >http://www.frameusers.com/ for more resources and info. Dennis Brunnenmeyer Director of Engineering CEDAR RIDGE SYSTEMS 15019 Rattlesnake Road Grass Valley, CA 95945-8710 Office: (530) 477-9015 Fax: (530) 477-9085 Mobile: (530) 320-9025 eMail: dennisb /at/ chronometrics /dot/ com
