When combining multiple blog feeds into one using Yahoo Pipes, is it possible to control the image sizes in the output?
I've seen the existing operators and filters offered, but there doesn't seem to be an option that e.g. rejects a post from my feed if its image is >500px wide, or even resizes that image to a given size.
I figured it out by the way - the solution is to use the Regex module to substitute existing width and height values for new ones. See this pipe: http://pipes.yahoo.com/strangerpixel/lcfcombo.
Related
Noticed that images sometimes are sliced up in PDFs.
Steps:
insert an image with a high resoultion (3000x1800) into a .docx
use "Microsoft Print to PDF" option of Word to convert to PDF
extracting all images with pdfimages or pymupdf
Result:
Image is sliced horizontally into three images
Questions:
What exactly happens in the in the transition from .docx to pdf (or in generell in the process to pdf) that makes the converter slice it up into three images instead of one?
Do the individuell XObjects of the sliced images contain information which says that these three images belong to originally one?
How do I know how the images are sliced (horizontally / vertically) and what if originally there were two images inserted into the .docx file and both of them are sliced. Can you tell if slice x belongs to original image y or z?
So, as you have found out: because the code which generates the PDF choose to do so.
The technical reasons may be various - it could be that historically there were printers which would only have so much memory, and would need to get limiterd size-images when printing, and someone at some point when writing the PDF export code present in Microsoft Office choose to apply this limit.
Anyway, technically, as put in the comments, an image in a PDF file could be composed of unlimited smaller images collated together.
Now, the second part, and your actual question: to know whether images ibn a PDF file belong together in a single original image one would need a custom extractor tool to check the geometry of all images in the document and find out which images have no margins or boundaries with others - it would not be that hard to do for well behaved files (which we can't know if MS Office generated files are: there are ways to obfuscate image positioning by making it indirectly). The metadata in the image-parts may or may not contain information that would allow one to recompose the original image: it would be up to the code generating the PDF to include this metadata or not - but the geometry can't lie in this case: if the final document presents a single image visually, it is possible to detect that when fetching the images.
I need to take an existing PDF (created with Prawn), and combine pairs after page 1 (the cover) into single pages. I would also like to add a vertical line in the center of the joined pages. The pages are to be printed in books, and the goal is to make single PDF pages that are similar to the side by side view in Acrobat. I know I can convert them to images, do what I need to with ImageMagick, then put them back into a PDF format, but I am trying to minimize the number of conversions so I can save as much quality as possible.
I also realize I can do this from the start with Prawn, but I am trying to avoid that as it would require a very large change to our application.
It is possible to do this with Ghostscript and the pdfwrite device, but its by no means simple. You need to write some PostScript to do the job.
You would need to add BeginPage and EndPage procedures, the BeginPage would need to check the current page number (and you would need to track this yourself). If its page 1, process normally. If its an even page, throw away the current PageSize and replace it with one which covers a pair of pages. Process the even page. Do not transmit the content.
If the page is odd (and not 1) then translate the origin so that its offset to the right by the width of the page. Process the odd page. use moveto, lineto and stroke to draw the required line between the two pages. Transmit the page.
This assumes that all the pages are the same size and orientation, or least that the sizes of each page are known in advance. It would be possible to retrieve those programmatically as well, but more complex.
Its definitely non-trivial, but if you rummage through my answers in the PostScript tags and look for anything with the word 'imposition' you'll probably find program outlines to do the job.
I did a quick look and here's an answer I wrote some time back. It uses a different approach to that outlined above, it copies some of the guts of the PDF interpreter and repurposes them. It does a chunk of what you want though.
I'm currently trying to achieve this:
I have a very large TIFF image, which contains scanned documents. The image contains invoices with barcodes/QR codes, followed by multiple other scanned documents related to the invoice which preceded them. This can be repeated multiple times ( the TIFF image may look like [invoice] + [documents] + [invoice] + [documents] ... )
I need a program (doesn't really matter in which language but I'd prefer either Java, JavaScript, PHP, C++ or Python) that takes said TIFF image, scans all the barcodes and returns their values and their position in the image (either which page it is on or it's absolute position, but the page is preferable, I know for certain that there won't be multiple barcodes on one page). The goal is to split this TIFF image into multiple PDF files, each containing only one invoice and all of the documents that belong to the invoice.
I have the latter part done already. I intend to use ImageMagick to split the TIFF file into multiple files (tested, works). I have also tried multiple barcode scanning methods, but met critical problems at every one. And that's the point of my question:
Is any of my presumptions false? Is there a better way/library/SW that you know about that could work?
Libraries/SW I tried so far:
ZXing port for PHP: Can't work with TIFF files
ZXing github
Quagga for JavaScript: Can't work with TIFF files either.
Quagga github
ZBar code reader: The best looking one by far. I managed to scan multiple QR codes in one TIFF image using CMD (Windows), but didn't find a way to get their positions. Also found out that C++ and Python versions exist, but didn't get to try them out just yet.
Thanks for any ideas/corrections.
The best one I heard -that is subjective ofc- is Barcode Rendering Framework
I'm not sure if it can detect multiple barcodes on a page but it can detect many different types of barcodes.
And it's also Open Source..
How do I do something similiar to the above photo programmatically, say using Python, JavaScript, PIL, ImageMagick, etc? Also is there a term for such an effect which would help me google it?
I've read much about PDF extractions and libraries (as iText) but i just haven't found a solution to extract images and text (with coordinates) from a PDF.
The task is to scan PDF with catalog of products and extract each image. There is an image code printed next to each image and also a list of product codes for products that are shown on the image.
I know that there is no way to extract structured info from a PDF like this but with coordinates of all image and text objects I could write code to identify linked text by its distance from the image. Then I could split text using a RegExp and find out what is a product code, what is an image code etc.
Could you recommend a good and working solution for the task?
Use XPDF (http://www.foolabs.com/xpdf/)
It can extract all the characters in the PDF with co-ordinates (pdftotext -bbox [sourcefile] [outputfile]) and also all the images and SVGs in the PDF.
It's open source (GPLv2) and supports a lot of additional extraction functionalities as well.
Several Java libraries can do this. Have you looked at JPedal or PdfBox?
If a commercial library is an option for you, you could try Amyuni PDF Creator .Net or Amyuni PDF Creator ActiveX. You could use the method IacDocument.GetObjectsInRectangle to retrieve all the "graphic objects" of your interest, then use the ObjectType attribute to separate images from text. The library already provides an algorithm for putting close text together. From the documentation:
IacDocument.GetObjectsInRectangle Method
The GetObjectsInRectangle method gets all the objects that are in the specified rectangle.
Usual disclaimer applies.