Book Design and Imaging

Compression question

I not sure why this happened. Any help would be appreciated.

 

I uploaded my first book. I had carefully prepared all my images so they were exactly the same pixel dimensions as the ‘optimal image size’ shown in the placeholders. Maybe I misunderstood, but on my reading of the forums, I was expecting they would not therefore be altered in any way when I uploaded them. However, although my book is 140Mb on my computer, booksmart did some ‘preparations’ (presumably compression of some sort) and then uploaded only 52Mb.

 

So does Booksmart always compress your images, regardless of how you prepare them, or is there any way you can make the program not compress your images? I would far rather compress my images myself if anyone is going to do it!

 

Thank you

 

Ronny

 

(Sorry this repeats my earlier posts, which started with a whole lot of garbled text that did not show up in the preview).

Replytopic_b_normal
Posted by
JulBarnard
Nov 30, 2008 9:06am PDT
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JulBarnard
 

Know that all photos use compression, period.  Otherwise a 7×7 inch photo at 300 dpi would require 13 Mb instead of the usual 2-4 Mb.  So compression is applied, always, to frustratingly caying degrees.

In addtiion, I’d assume that LOSSLESS compression is used on the prepped copy to minimize bandwidth. Essentially, the upload is ZIPped up.  JPG & MPG compression scheme, unlike most compression method, are lossy.  The more they compress, the more data they change, lowering quality.  I think that is what you are thinking of.  However there are many compression algorithms, that simply compact data, optimizing space to represent EXACTLY what it is. ZIP, LZW, Stacker, there are dozens of them, each optimized for a particular application.

When I BACKUP/EXPORT my book, which preserves all the full original photos, it results in a 1.39 GB file. However, the book includes 1.59 GB of image data. So clearly, a compression algorithm is being used when backing up the book. I’d expect they would do the same before uploading to speed up the upload process.  My upload was less than 500MB, and at least half of my photos were much larger than the needed resolution.

How you measured size on disk could also add to the confusion. Your Booksmart directory contains a Library with 4 copies of every image. For my 1.59Gb of images there were about 250 mb more of smaller sized copies, none of which are used in the upload process.  Only the originals would play any role.

I imagine there will be some difference depending upon the compression quality they use in the final bitmaps generated for each page. It would be interesting to know technically. 

Posted by
royalef
Dec 1, 2008 2:42pm PDT
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royalef
 

Thank you for replying.

 So, if I understand correctly,  even if my images have the exact optimum pixel dimensions for the placeholders in Booksmart, they will be further compressed when the book is uploaded. (As you say, they have already been compressed once, because they are required to be saved as JPEGs, which is a compression format).

If the compression is lossless, no problem. If not, then that would be a major disadvantage of Booksmart. The user would have to accept a loss of quality, to save bandwidth.

Does anyone know for sure whether the compression is lossy or lossless?

Thank you

Ronny

 

Posted by
JulBarnard
Dec 5, 2008 11:23am PDT
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JulBarnard
 

Ronny,

To put this way more simple approach, all JPEG files are compressed. This means it destroy true native raw photo file you took/shoot with your camera. If you continue to edit on compressed JPG pictures and then it continues to compress more, this destroy much further.

Always a GOOD idea to keep all ORIGINAL photo files and save them somewhere, on your DVD, backup hard drives.

I work with all of my photos as Nikon Electronic Format as in .nef which means RAW format for Nikon dSLR camera I use… I also convert all of these photos from NEG format to TIFF (no compression included, NONE).

While you are working with photos, that you wanted to pick some photos used for your book, copy these photos… work with them in Photoshop using TIFF format… if you are done with workflow, you want to save these photos as in HIGH QUALITY JPG (or PNG format), then import them into Booksmart.

As for Booksmart’s handling of its JPEG format is totally beyond what we can handle. And there are so many discussion related to this issue fairly often on the topic. Perhaps that you also want to do some reading after search on the topic.

Hopefully that helps, no?
Cheers, Brian {a passionate Blurbarian}

Posted by
brianbonitz
Dec 5, 2008 3:33pm PDT
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brianbonitz
 

Basically, JPG is a lossy format. 

However the upload process may not be compressing the book (text, format and photos) in any lossy way for upload to the server.But I imagine they do ZIP it up to optimize the upload. 

 

Posted by
royalef
Dec 5, 2008 8:32pm PDT
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royalef
 

Perhaps that you want to submit an enhancement request submission for feedback and suggestion with Blurb Team for this issue.

While zipping it up, it sounds like a brilliant idea.

Brian {a passionate Blurbarian}

Posted by
brianbonitz
Dec 5, 2008 8:36pm PDT
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brianbonitz
 

I’be interested to find out what is going on for upload as well.  If you have over 1GB of phots, it is strange that the upload would be less than 500MB.  Even if they zipped up the entire contents of the book, it doesn’nt make sense.  Since JPEGs are already compressed, zipping (or compressing them in some other method) them will not result in any noticeable reduction in file size.  You can’t compress what is already compressed, at least, not very much.  If you take a collection of photos that equal 100MB in size, then add them to a zip file, the resulting zip file might be around 98MB or so, but not much less than 100..

Posted by
lctalbot
Dec 11, 2008 3:44pm PDT
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lctalbot