Re: [Frameworks] DPI
No, Gene, that's the absolute number of pixels, not the size of the image when printed. DPI is the number of dots per inch. It should actually be referred to as PPI or pixels per inch. (DPI is number of printer ink dots, which is different from the size of a pixel.) PPI is a setting in the file header that tells a printer how big a pixel should be printed. The PPI setting is completely independent of the number of pixels. Looking at an image on your screen, zoomed at 100%, you will see the image pixels mapped one-to-one onto your display. You will not be able to visually ascertain how large that image will be when printed. When zoomed at 100%, a 300 pixel image @ 300 ppi looks the same as a 300 pixel image @ 96 ppi. The PPI setting also can be used to emulate the size of a printed page (Photoshop zoomed to actual size) but this is often wrong because the app doesn't know enough about the display device to be accurate. An image that is 300 pixels wide @ 300 ppi will print out to be one inch wide. An image that is 300 pixels wide @ 96 ppi will print out to 3 and 1/8 inches wide. ( 300 / 96 = 3.125 ) I wrote an article explaining this in more detail. http://digitalartsguild.com/index.php/resources-menu/articles-resources-menu/71-digital-images-101?showall=start=3 Regards, Aaron At 7/1/2015, you wrote: Friends, am I assuming correctly that when you âget infoâ about the properties of an online photo, âdimensionsâ (i.e., 400 x 500) refers to DPI? ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks -- Aaron F. Ross, artist and educator http://dr-yo.com http://digitalartsguild.com ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks
Re: [Frameworks] DPI
Hi Gene, The dimensions you quoted look like pixel dimensions. DPI is a term from the printing industry that refers to a physical manifestation (dots per inch). It doesn't really apply to digital manifestations of an image. The corresponding digital term would be ppi (pixels per inch) which is an attribute of a display device rather than a file - although files can have a specified ppi, in practice unless we are creating a physical manifestation, it has little meaning. So in the purely digital realm, if left unscaled, that 400x500 image file will have very different sizes depending on the ppi of the display device: The the LCD on the laptop I'm typing on has 107ppi: 3.74 x 4.67 iPhone6 (326ppi): 1.23 x 1.53 iPhone6plus (401ppi): 1 x 1.25 A 60 1080p TV (37 ppi): 10.81 x 13.51 The little iPhone6plus has the same number of pixels as a gigantic 60 1080p HDTV, so that 400x500 image will be 1 inch wide on the phone and almost 11 inches wide on the TV. -Hope that helps, --Buck Bito Lawrence Buck Bito Movette Film Transfer 1407 Valencia St. San Francisco, CA 94110 (Valencia at 25th St.) 415-558-8815 Open Tuesday - Saturday Tue+Thu: 8-6, Wed+Fri: 9-6, Sat: 10-4 www.movettefilm.com On Wed, July 1, 2015 10:24 am, Gene Youngblood wrote: Friends, am I assuming correctly that when you get info about the properties of an online photo, dimensions (i.e., 400 x 500) refers to DPI? ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks
Re: [Frameworks] DPI
Thanks very much, Buck and Aaron, for your informative explanations. On Jul 1, 2015, at 11:56 AM, Aaron F. Ross aa...@digitalartsguild.com wrote: No, Gene, that's the absolute number of pixels, not the size of the image when printed. DPI is the number of dots per inch. It should actually be referred to as PPI or pixels per inch. (DPI is number of printer ink dots, which is different from the size of a pixel.) PPI is a setting in the file header that tells a printer how big a pixel should be printed. The PPI setting is completely independent of the number of pixels. Looking at an image on your screen, zoomed at 100%, you will see the image pixels mapped one-to-one onto your display. You will not be able to visually ascertain how large that image will be when printed. When zoomed at 100%, a 300 pixel image @ 300 ppi looks the same as a 300 pixel image @ 96 ppi. The PPI setting also can be used to emulate the size of a printed page (Photoshop zoomed to actual size) but this is often wrong because the app doesn't know enough about the display device to be accurate. An image that is 300 pixels wide @ 300 ppi will print out to be one inch wide. An image that is 300 pixels wide @ 96 ppi will print out to 3 and 1/8 inches wide. ( 300 / 96 = 3.125 ) I wrote an article explaining this in more detail. http://digitalartsguild.com/index.php/resources-menu/articles-resources-menu/71-digital-images-101?showall=start=3 Regards, Aaron At 7/1/2015, you wrote: Friends, am I assuming correctly that when you âget infoâ about the properties of an online photo, âdimensionsâ (i.e., 400 x 500) refers to DPI? ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks -- Aaron F. Ross, artist and educator http://dr-yo.com http://digitalartsguild.com ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks ___ FrameWorks mailing list FrameWorks@jonasmekasfilms.com https://mailman-mail5.webfaction.com/listinfo/frameworks
