[Leica] that pesky megapixels and megabytes conundrum for the Yearbook

[Lluis Ripoll]

My friend,

After your detailed explanation I assume that I’m selling at 0,000008333 Euro per Pixel …. TOO CHEAP!

I’m preparing 15 pictures to be exposed in a Bar… I’m busy…

Just a joke…

Cheers!
lluis


El 03/11/2014, a las 23:10, Geoff Hopkinson <hopsternew at gmail.com> escribió:

> As the first contributions arrive for our Yearbook it appears that there is
> some confusion on the specifications for the image files that people are
> sending. Don't panic! Everything sent is in our book.
> 
> It might be worth revisiting some concepts for clarity and everyone's
> convenience.
> Here is an example.
> An image file  6000 pixels x 4000 pixels has a total pixel count of 24 000
> 000. That is 24 million pixels or megapixels.
> The resolution (number of pixels per inch) only affects the physical
> dimensions of a print or on a computer screen. In the case of the LUG
> Yearbook 3000 pixels would print to be 10 inches wide if the page was large
> enough.
> 
> Assuming the same pixel dimensions the file size in megabytes (millions of
> bytes) can vary enormously. That is affected by how the image information
> is stored and in what format. (raw file or JPEG for example).
> 
> Starting from a raw file from your camera or a TIFF format image perhaps
> you can make a smaller version of the image in the JPEG format by varying
> two things.
> Resample the file to a lower number of pixels, for our example 6000 x 4000
> pixels to 3000 x 2000 pixels (a 6mp image)
> Change how much compression is used in the conversion. Higher compression
> means more loss of original information but a smaller file in megabytes.
> 
> Files that are much too big in megabytes will not result in higher quality
> reproduction. Blurb will just throw away that information basically. The
> posted guidelines of files between one and two megabytes are meant to help
> ensure sufficient information for quality when printed while controlling
> the file sizes both for email transmission and the overall book file size
> as it has to be uploaded by me of course. Files larger than necessary get
> shrunk by Blurb prior to transmission when the whole book file is uploaded.
> That file can get very large.There is no user control over that shrinking.
> 
> The Blurb software does several things with image files put on the page.
> By my choice as the compiler your images are not cropped nor expanded to
> fit the whole space. The only loss of any part of the image is where the
> full bleed option is used on the left hand page. That means that there is a
> small overlap of unprintable pixels at the edges to ensure that the
> printing goes right to the edge of the paper.
> 
> When your image is not the same proportions as the page 'frame' they are
> being put into the longest dimension in pixels gets downsampled to the
> maximum number of pixels of the longest side of that page fame. That
> usually means that there is some unused area within the frame. You can
> choose to crop your images anyway you want of course. Some people may want
> to crop to match the exact proportions of the offered Blurb frames and/or
> downsample their image so that the long dimension in pixels matches that of
> the long dimension of the frame.
> 
> Clear as mud?????
> 
> 
> 
> Cheers
> Geoff
> http://www.pbase.com/hoppyman
> 
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