[Decapod] Image scaling and transformation of mixed content
boyan.sheytanov at asteasolutions.com
Mon Mar 1 13:33:27 UTC 2010
My comments are inline below.
On 26 February 2010 16:56, Thomas Breuel <tmbdev at gmail.com> wrote:
> > Image 1: 1200x2000 (content area: 1100x1900)
> > Image 2: 1300x1700 (content area: 1200x1600)
> I don't see how this can occur with our current use cases. Neither
> Book Liberator nor stereo generate these kinds of images. It also
> doesn't happen with flatbed scanners or common book scanners, if
> people used those to generate the original scans. And it doesn't
> generally happen with the scanned books people can download from
> Google or the Internet Archive.
I guess that the two images will always be the same size, but after cropping
the resulting images might be different sizes (that will differ with several
pixels in the general case). At least these are my impressions after doing
automatic cropping with BookLiberator software on some sample images found
on their site.
> > What if the user imports 100 pages. Page 1 is 800x600. Page 2 is
> > 3 to 99 are 1200x2500, and the last one is 3000x5000.
> Dealing with mixed size originals is out of scope for the entire
> project and it is far more complex than the simple image editing
> operations we need for books (where all pages are the same size).
I agree with Thomas. If the user imports images with different sizes, it's
his problem. We only need to clearly document this.
> > Do we apply the dimension transformation to ALL images, or do
> > transformations apply to just a pair/spread?
> Approach 3: return an error message.
We only do the dimension transformation because we want to stitch to equally
sized images. There's no point in applying in to all images.
> > Question:
> > What effect does different page / image sizes have on PDF and TIFF
> > generation?
> I don't know and can't predict either. We're assuming that the
> originals are books, scanned consistently by the same process at the
> same resolution.
For TIFF I believe there's no effect other than having a multi-page TIFF
file containing images with different size. Basically, the TIFF format is
just a container so it shouldn't be interested in the sizes of its content.
Same might be true for Image-only PDF, not really sure about it though.
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