What’s up with the megapixels?


This was just a spontaneous experiment (which captures my idea, but not with the quality I hoped for). But once I did it, I was confused.   I took this (these) photo(s) (of bookshelves in my office) with my iPhone in the app called Duomatic (an app I’m not at all impressed with, but which interested me nonetheless).  The app combines two images into one.  I processed in iColorama (an app with lots of a great features that I enjoy very much) and then tried to save the image a bit (without much success) in Lightroom.  Anyway, what I’m confused about is the megapixels.  The primary camera on the iPhone 4s is  8 Megapixels.  This photograph is only .5 megapixels (yes, that’s point 5).  How can that be?  I did take the picture with the primary camera (not the front camera, which I know has a significantly reduced number of megapixels).

24 responses

  1. Mhm – I don’t know your technical knowledge… Maybe you mix up some things…
    8 Megapixel (number of all picture-dots in the matrix of all rows an columns) means – for example length’s of the picture edges of 3264 × 2448 dots (for the common edge-rate of 4:3).
    A software application is of course able to re-calculate this lenght’s for less size, if you advise it so. But of course you loose a lot of informations. If you’d advise the Software to halfen the length’s of the edges, the Software makes one pixel out of 4 and the Information density is only fourth Part in result.
    This might happen within one of your picture Editor apps. Perhaps there exist hidden settings that you can preset.
    The other possibility, that comes to my mind: Is it possible, that you mix up density (Megapixels) and File size (measured in Megabyte)? An 8 Megapixel picture might have around 0.5 Megabyte filesize, when saved as jpg-File with middle quality.
    Hope I have been able to help…

    September 21, 2013 at 2:18 pm

    • I downloaded you “bookshelfs” and had a look on. It’s in deed around 0.5 Megapixels (890×583 pixels). It must have been downsized by one of the apps. Some apps do this automatically when used as trial versions. My Smartphone is Android based – can’t check the iPhone stuff…

      September 21, 2013 at 2:24 pm

      • Thank you, Stefan, for your detailed comments. I really appreciate the information. It’s not boring at all (as you commented after this). I think what makes most sense in this case is that I was using the “lite” version of the app, and I think that the image was indeed downsized, as you suggested.

        September 22, 2013 at 1:55 pm

  2. I have no answers to your technical questions, but I do like the shot. I love double exposures and if I had a camera that could do them, would be taking them too.

    September 21, 2013 at 2:58 pm

    • I’m glad you like the shot. I will experiment with the idea a bit more. Thanks for the visit!

      September 22, 2013 at 1:56 pm

      • I was first inspired to want to shoot double exposures when I saw a photo of Sandra Bartocha’s in the Wildlife Photo of the Year contest in 2011 (you can find it on their website, but I can’t make a sensible link to it). Many of her flower shots on her own website are done this way, and are wonderful

        September 22, 2013 at 3:23 pm

        • Wow! Her photographs are amazing! Thanks so much for sharing the link! I’m all inspired now.

          September 24, 2013 at 8:17 pm

  3. Very interesting. It reminds me of an old film, the ones where you have weird dream sequences and the protagonist is clutching his/her head in an agony of affliction. Exams maybe? 😉

    September 21, 2013 at 3:19 pm

    • I’m eager to experiment with this effect more. I like what you’ve said about the dream sequence. And yes, :-), my students may indeed be clutching their heads in agony. Exam time is right around the corner. 🙂

      September 22, 2013 at 1:59 pm

  4. Cool!

    September 21, 2013 at 4:15 pm

  5. Licht… ‘s explanation might be still complicated for you.
    Just have a test shot of completely black and other, white
    and see how big the “file” is. Then make this book shelf photo
    only in black or white (highest contrast) and see the size of file.
    You may get some idea “how information size” makes the size of FILE, not by the Pixel number.
    The out-put of image information from the camera is not proportional to the number of pixels,
    as Licht… said, it involves quite complicated process to make it as small as possible.
    ( In fact, one pixel consist BGGR (yes 4) dots of photo-sensor, and the out-put,
    if it has really 12 ~ 16 bit depth, the original information size is Enormous. —- but nobody needs
    such information, as our eyes couldn’t distinguish more than 1000 colors, and anyhow
    the screen couldn’t display it. = it has to be downsized.)
    So that, practically we don’t need more than 3 mega pixels though, the people is believing that the
    more pixels the better = this false belief has been exploited by the camera maker to sell.

    September 21, 2013 at 4:36 pm

    • Thank you, Yoshi-sensei for offering this explanation. I will try the experiment you mentioned. I think the issue with this particular image was that I was using a free app, and therefore the resolution of the image was very poor. Interesting the point you make about not needing as many mega pixels as camera makers make us think. I plan to stop over for a visit to catch up with your blog soon.

      September 24, 2013 at 8:13 pm

  6. I wonder what this would do to something like an old barn.

    September 21, 2013 at 5:32 pm

  7. I think Yoshizen’s explanation complements Licht. . . .’s quite well. For example, you will notice that the file size of any photo goes up whenever you process it in certain ways, such as sharpening it. The resultant detail calls for more pixels in the final image, or at least that is my guess.

    September 21, 2013 at 5:33 pm

    • I’m sorry to say – but this is a wrong guess…
      It can happen, that processing of a picture increeses the file size (if saved with the same application and presets in both cases). But a software application is never able to increase picture informations. When you sharpen a picture (or modify it however), the pixels are only modified in their colors. The “improvement” is only a “trick of the light”, depending on the knowledge of how our eyes and brain interprete the given Information.
      The increase of filesize depends on the functionality of the packing algorithm of the jpg-file. If one example pixelrow is originally completly white, and has – after processing – shades of grey, the jpg-compressor can’t group this Information any more and the file size increases.
      All very technical stuff – I hope it’s not boring. But you did ask… 😉

      September 22, 2013 at 12:49 pm

  8. It’s not the camera Melanie it’s the app. That happens to me a lot. Certain apps especially free ones saves the image once processed at a low resolution.

    September 21, 2013 at 5:44 pm

  9. I like the double-exposure effect too, but I wanted to see the titles… 🙂

    September 21, 2013 at 6:21 pm

    • Ah, but the titles would be far too revealing for such a public space as this… 😉

      September 24, 2013 at 8:14 pm

  10. The fading memories of all the books you’ve ever read… Very cool!

    September 21, 2013 at 8:23 pm

  11. no matter the size, it looks awesome

    September 22, 2013 at 6:57 pm

  12. Great image, whatever the megapixels.

    September 22, 2013 at 7:51 pm

    • Thanks, Richard. Yesterday (or the day before, I’m losing track), I took a spin around your blog. Great stuff happening over there. I WILL catch up. 🙂

      September 24, 2013 at 8:15 pm

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