{"id":164,"date":"2004-09-19T23:01:25","date_gmt":"2004-09-19T15:01:25","guid":{"rendered":"http:\/\/www.nargalzius.com\/blog2\/http:\/www.nargalzius.com\/blog2\/archives\/2004\/09\/2004_09_19_2301.php"},"modified":"2004-09-19T23:01:25","modified_gmt":"2004-09-19T15:01:25","slug":"the-truth-of-the-megapixels","status":"publish","type":"post","link":"http:\/\/nargalzius.com\/blog\/archives\/2004\/09\/19\/the-truth-of-the-megapixels","title":{"rendered":"The truth of the megapixels"},"content":{"rendered":"<p>&#8220;Canon EOS 20D&#8221;<\/p>\n<p>&#8220;Canon EOS 300D \/ Digital Rebel&#8221;<\/p>\n<p>I lent <a href=\"http:\/\/www.nonofelipe.ph\" title=\"Visit site\">Nono<\/a> my <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=10464\">20D<\/a> for [what was soon to be considered] the last Ateneo &#8211; La Salle UAAP game.<\/p>\n<p>Before I continue&#8230; let me tell you now that he&#8217;s the <em>only<\/em> person I can trust with my cam (without me physically present that is), so for those who want to borrow it &#8211; <strong>forget it!<\/strong><\/p>\n<p>Anyways, he noticed something about the &#8220;resolution.&#8221; The <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=10464\">20D<\/a> stores its images @ 72<code>dpi<\/code> (Dots Per Inch), while the <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=9430\">300D<\/a> stores <em>its<\/em> images at 180<code>dpi<\/code>.<\/p>\n<p><em>What gives?<\/em><\/p>\n<!--more-->\n<p>&#8220;Canon 1Ds&#8221;<\/p>\n<p>&#8220;Canon 1D MarkII&#8221;<\/p>\n<p>&#8220;Canon EOS 20D&#8221;<\/p>\n<p>&#8220;Canon EOS 300D \/ Digital Rebel&#8221;<\/p>\n<p>I had an inkling of a possible explanation from my experience with Photoshop before, but I never got to confirm it&#8230; until he pointed me to this reply.<\/p>\n<p>The whole thing was better explained by the &#8220;pros&#8221; in our mailing list:<\/p>\n<blockquote>\n<p>The dpi (or ppi) is actually secondary. It is the number of pixels\nthat really matter. The 300D produces images made up of 6 million\npixels, the 20D produces images of 8 million pixels. The dpi just\nrefers to the arrangement of those pixels? How dense are they\narranged. 72 dpi is the resolution for viewing images on the web, or\non your computer. 300 dpi is the resolution recommended for\nprinting. There is no loss when your camera dishes out the image as\n72 dpi or 180 dpi as the total number of pixels remain the same.\nIf you want to rearrange the density of the pixels,\nGo to photoshop, select IMAGE \/ IMAGE SIZE. A dialogue box pops up.\nUncheck RESAMPLE IMAGE. In the box for RESOLUTION place the number\nof pixels you want your image to be arranged at (300 dpi, 72dpi,\netc). Notice that the height and width of the image will change. The\nhigher the value of the pixels per inch, the smaller the resulting\nimage will be. The smaller the value of the pixels per inch, the\nlarger the image size will be.\nNo loss will occur because the same number of pixels that comprise\nthe image remain. They are just arranged differently.\nOh, click ok to exceute the command.<\/p>\n<\/blockquote>\n<p>Fortunately, I understand it now (thanks to the post and some more fiddling with photoshop and a calculator), and I can offer a somewhat layman explanation &#8211; though extremely long and detailed.<\/p>\n<p>It turns out that they [<code>dpi<\/code> and camera resolution] are totally unrelated as far as the digital image is concerned. Since when talking digital images, you&#8217;re talking about camera\/sensor resolution. 8<code>MP<\/code> at <strong>any<\/strong> <code>DPI<\/code>, is still 8<code>MP<\/code> and does not change in quality since pixels are like &#8220;atoms&#8221; in digital imagery &#8211; you can&#8217;t make a pixel hold <em>more<\/em> detail than any other pixel, nor can you break it down to smaller units. Given the current pixels available to you (8<code>MP<\/code>, 6<code>MP<\/code>, whatever) it&#8217;s up to the sensor and processor to assign those values to the individual pixels&#8230; and <em>that&#8217;s<\/em> what affects sharpness, color, or detail.<\/p>\n<p>So where does <code>DPI\/PPI<\/code> come into the picture?<\/p>\n<p><code>DPI\/PPI<\/code> (Dots Per Inch \/ Pixels Per Inch) are related to <em>print resolution.<\/em> Meaning that on a piece of paper, how many points are crammed\/printed into an inch.<\/p>\n<p>Yet <code>DPI<\/code> and <code>PPI<\/code> are <em>further<\/em> differentiated. <code>DPI<\/code> is printer specific, while <code>PPI<\/code> is the more appropriate term for the <em>image&#8217;s print setting<\/em> itself. However, it has been common practice to use <code>DPI<\/code> lightly and represent <code>PPI<\/code> most of the time. Image EXIF data [incorrectly] denotes the <code>PPI<\/code> as <code>DPI<\/code>.<\/p>\n<p><code>PPI<\/code>, <code>DPI<\/code> and all that jazz only will apply if you intend to print something. It is good practice to use the pixelcount <em>in conjunction with<\/em> the <code>PPI<\/code> you intend to use, to clarify things.<\/p>\n<p>This is where <code>PPI<\/code> is important &#8211; assuming you have enough [mega]pixels to match your print resolution, the higher the <code>PPI<\/code>, the more &#8220;fine\/detailed&#8221; your print will be. I had to mention megapixels matching print resolution because you can always try printing an 640&#215;480<code>px<\/code> (1<code>MP<\/code>) image at 300<code>ppi<\/code>&#8230; you&#8217;ll get a really small (2&#215;1.5<code>in<\/code>) picture. &#8220;Fine&#8221; probably, but hella small.<\/p>\n<p>Simply put, any pixelcount can be printed a number of ways without <em>resampling<\/em> (changing the pixelcount, ergo <em>retaining<\/em> the <strong>original<\/strong> quality of the image). A 300&#215;300<code>px<\/code> picture can be printed as a 1&#215;1<code>in<\/code> picture using 300<code>ppi<\/code>&#8230; or larger using a smaller <code>PPI<\/code> setting &#8211; yet it still is the same 300&#215;300<code>px<\/code> image with no modifications whatsoever.<\/p>\n<p>Having difficulty imagining it? Think of it this way. If you had a black 1&#215;1<code>px<\/code> image, and print at 1<code>ppi<\/code> (assuming it&#8217;s possible) &#8211; then you get <strong>a square inch<\/strong> of blackness (representing that <em>single<\/em> pixel). If you increase the <code>PPI<\/code>, it gets smaller.<\/p>\n<p>If you print a 300&#215;300<code>px<\/code> image at 300<code>ppi<\/code>, then you&#8217;d <em>also<\/em> get a square inch, but this time the <em>whole<\/em> 300&#215;300<code>px<\/code> image will be printed on that square inch.<\/p>\n<p>This is where pixels and <code>PPI<\/code> are relative to each other in digital photography <em>printing.<\/em> The higher the <code>PPI<\/code> translates to &#8220;finer&#8221; printing, because it can print more dots per square inch (duh!)<\/p>\n<p>For printing (magazine, poster, etc.), the standard is 300<code>dpi\/ppi<\/code>. So anyone trying to print pictures will most probably be trying to print at that &#8220;resolution&#8221; <em>at the very least.<\/em> You can use more (or less), but 300<code>ppi<\/code> is pretty much a safe standard since the eye, more often than not, <em>cannot<\/em> discern the individual printed dots\/points beyond 300 per inch.<\/p>\n<p>From that alone, assuming you know how you want to print your stuff, you can pretty much calculate how much [mega]pixels you need for your prints. Just multiply your intended print quality (<code>PPI\/DPI<\/code>) to your intended print <strong>area.<\/strong><\/p>\n<p>Before I continue, let me paste these sizes (for future reference, yes even <em>my<\/em> future reference as I have lousy memory).<\/p>\n<pre>\nPRINT SIZE              PHOTOSHOP FILE\n3R = 3.5\" x 5\"          = 4.45\" x 6.25\"\n4R = 4\" x 6\"            = 3\" x 4.5\"\n5R = 5\" x 7\"            = 4.5\" x 6.25\"\n6R = 6\" x 8\"            = 6\" x 8\"\n8R = 8\" x 10\"           = 8\" x 10\"\n<\/pre>\n<p>All in <strong>inches.<\/strong> The first column lists <em>actual<\/em> print sizes, next is the allowance in size you need in PS if you intend to have some printers print it (they sometimes crop your file). Though the second column may not be necessary for all people, I just included it in case it becomes applicable.<\/p>\n<p>Now where were we? Ah yes. Say you wanted to print a 4R picture (4&#215;6<code>in<\/code>). 4<code>in<\/code> @ 300<code>ppi<\/code> is about 1200<code>px<\/code>, and 6<code>in<\/code> @ 300<code>ppi<\/code> is about 1800<code>px<\/code>. But we&#8217;re not done yet! We need the <em>area<\/em> for the total amount of pixels needed. So 1200<code>px<\/code> multiplied by 1800<code>px<\/code> is 2,160,000 pixels or 2.16 megapixels. So the 2<code>MP<\/code> cameras are ok already to print 4x6es (at 300<code>ppi<\/code>), and those 4-5<code>MP<\/code> cameras are more than decent for everyday photography&#8230; and that&#8217;s assuming you <em>absolutely must<\/em> print at 300<code>ppi<\/code>.<\/p>\n<p>Using the same math, approximately 7.92 megapixels are needed to print an 8&#215;11<code>in<\/code> (letter sized) at 300<code>ppi<\/code>. So the <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=9808\">1D MarkII<\/a> and <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=10464\">20D<\/a> as of the moment, with their 8<code>MP<\/code> sensor count, are capable of such print resolutions. The <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=8280\">1D<strong>S<\/strong><\/a> can print up to 10&#215;12<code>in<\/code> with its stellar 12<code>MP<\/code> count. And can be had for as low as 7.7k USD hahahaha.<\/p>\n<p>But somewhere along the way, I&#8217;ve veered from my point. Point is that the <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=10464\">20D<\/a> indeed takes pictures at 72<code>ppi<\/code>, and if you print at 72<code>ppi<\/code>, that would yeild a whopping 33&#215;41<code>in<\/code> print! hahahaha. But you can always change the <code>PPI<\/code> to about anything&#8230; it&#8217;s all relative, and doesn&#8217;t change the fact that your pic was taken at 8 megapixels. But this is where <code>DPI<\/code> comes in.<\/p>\n<p>If pixelcount weren&#8217;t an issue (meaning we had all the pixels in the world at our disposal) then we could simply print way beyond the standard&#8230; say 3200<code>ppi<\/code>? Yes we can, but can the printer support it? Same goes if you try to print a 300<code>ppi<\/code> image to a printer with a much lower <code>DPI<\/code> capability (say a dot matrix printer hehehe). At the end of the day, it&#8217;s <em>always<\/em> a balance between the image&#8217;s pixelcount, the image\/software&#8217;s <code>PPI<\/code> setting, and the printer <code>DPI<\/code> capability when it comes to &#8220;what you need&#8221; for printing.<\/p>\n<p>As far as original image quality is concerned however, these can be considered as irrelevant. The default of 72<code>ppi<\/code> is more of a nuisance, as you have to change the value everytime you intend to print at 300<code>ppi<\/code> (or any other print resolution). Then again, even the <a href=\"http:\/\/consumer.usa.canon.com\/ir\/controller?act=ModelDetailAct&amp;fcategoryid=139&amp;modelid=9430\">300D<\/a> requires you to change it (since it starts at 180<code>ppi<\/code>). Yet, <strong><em>in no way whatsoever,<\/em><\/strong> does it affect the quality of the picture <em>in itself.<\/em> That would be the sensor\/processor&#8217;s job&#8230; and of course, the lens you&#8217;re using.<\/p>\n<p>There&#8217;s a good article explaining this in case my explanation doesn&#8217;t cut it: <a href=\"http:\/\/www.tildefrugal.net\/photo\/dpi.php\">http:\/\/www.tildefrugal.net\/photo\/dpi.php<\/a><\/p>\n<p>To sum up, I have come to a realization &#8211; gradeschool math isn&#8217;t useless after all! hahahaha.<\/p>","protected":false},"excerpt":{"rendered":"<p>&#8220;Canon EOS 20D&#8221; &#8220;Canon EOS 300D \/ Digital Rebel&#8221; I lent Nono my 20D for [what was soon to be considered] the last Ateneo &#8211; La Salle UAAP game. Before I continue&#8230; let me tell you now that he&#8217;s the only person I can trust with my cam (without me physically present that is), so &hellip; <p class=\"link-more\"><a href=\"http:\/\/nargalzius.com\/blog\/archives\/2004\/09\/19\/the-truth-of-the-megapixels\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;The truth of the megapixels&#8221;<\/span><\/a><\/p><\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[12,13],"tags":[22,31,35,740,1223],"class_list":["post-164","post","type-post","status-publish","format-standard","hentry","category-photography","category-technology","tag-1ds","tag-20d","tag-300d","tag-mark2","tag-uaap"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/posts\/164","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/comments?post=164"}],"version-history":[{"count":0,"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/posts\/164\/revisions"}],"wp:attachment":[{"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/media?parent=164"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/categories?post=164"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/nargalzius.com\/blog\/wp-json\/wp\/v2\/tags?post=164"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}