I have multi-page PDF-files with mixed formats A4 (portrait) - A0 (landscape).
Is Ghostscript capable of resizing the pages with size >A3 to A3 – but leaving the pages with smaller size (A4) not to be resized?
First, Ghostscript doesn't do manipulations of the input, you should read ghostpdl/doc/vectordevices.htm to see how Ghostscript and the pdfwrite device actually work.
Out of the box, no Ghostscript and the pdfwrite device won't allow you to produce output with differently sized media from the input, and different for each page (you can have it produce output sized to a single media size). It can, of course, be done, but will involve some programming, and in PostScript at that.
You would probably want to look at the pdf_PDF2PS_matrix routine in ghostpdl/Resource/Init/pdf_main.ps:
% Compute the matrix that transforms the PDF->PS "default" user space
/pdf_PDF2PS_matrix { % <pdfpagedict> -- matrix
...
Which calculates the scale factors required when resizing content to fit the media.
Also pdfshowpage_setup :
/pdfshowpage_setpage { % <pagedict> pdfshowpage_setpage <pagedict>
6 dict begin % for setpagedevice
% Stack: pdfpagedict
...
Which is where the selection of the media size takes place.
After spending long time looking for a solution, I found a great - and yet affordable - tool capable of doing the resizing and a lot more: PStill (http://www.pstill.com/)
Related
Using ImageMagick or GhostScript or any PHP code how can I get the DPI value of PDF files?
Here is the link for two demo files
http://jmp.sh/O5g5wL4 -- of 72 DPI
http://jmp.sh/RxrnYrY -- of 300 DPI
I have used
$image = new Imagick();
$image->readImage('xyz.pdf');
$resolutions = $image->getImageResolution();
It gives the same result for two different PDF files having different DPI.
I have also used
pdfimages -list xyz.pdf
It gives a list of all information but how to fetch the DPI value from the list.
How to get the exact DPI value of a PDF?
As fmw42 says PDF files themselves have no resolution. However in your case both the files consist of nothing but an image. In one case the image is ~48 MB and in the other its around 200 MB.
The reason is that the images have a different effective resolution.
In PDF the image is simply a bitmap, a sequence of coloured pixels. These are then drawn onto the underlying media. At this point there is no resolution, the pixels are laid down in a specific media size. In your case 22 inches by 82 inches.
The effective resolution is given by dividing the dimension by the number of pixels in the image in that dimension.
So if I have an image which is 1000x1000 pixels, and I draw it in a 1 inch square, then the effective resolution of the image is 1000 dpi. If I change my mind and draw it in a square 4 inches by 4 inches, then the effective resolution is 250 dpi.
The image hasn't changed, just the area it covers.
Now consider I have two images drawn in 1 inch squares. the first image is 1000x1000, the second is 500x500. The effective resolution of the first image is 1000 dpi, the effective resolution of the second is 500 dpi.
So you can see that, in PDF, the effective resolution of the image is a combination of the dimensions of the image, and the dimensions of the media it covers.
That's a difficult thing to measure in a PDF file. The area covered is calculated using matrix algebra and can be a combination of several different matrices.
The actual dimensions of the image, by contrast are quite easy to determine, they are given in the image dictionary. Your images are: 1620x5868 and 3372x12225. In both cases the media is the same size; 22.5x81.5 inches.
Since the images cover the entire media, the effective resolutions are;
1620/22.5 = 72 by 5868/81.5 = 72
3372/22.5 = 149.866 by 12225/81.5 = 150
I think MuPDF will give you image dimensions and media dimensions, assuming all your PDF files are constructed like this you can then simply perform the maths, but note that this won't be so simple for ordinary PDF files where images don't cover the entire media.
Using mutool info -I -M 150-dpi.pdf gives:
Retrieving info from pages 1-1...
Mediaboxes (1):
1 (6 0 R): [ 0 0 1620 5868 ]
Images (1):
1 (6 0 R): [ DCT ] 3375x12225 8bpc DevCMYK (12 0 R)
So there's your image dimensions and your media size. All you need to do is apply the division of one by the other.
Note: In debian and related distros, mutool is contained in mupdf-tools package, not in mupdf package itself. It can by therefore installed by sudo apt install mupdf-tools.
I use pdfimages -list from the poppler library, gives you all the information about the images.
I have PDF document with many pages 595x420 ppi but I need this pages push in 595x210 but all text must be visible.
So.. Can I change scale of PDF pages unproportionally (no zoom) to fit custom size of page with ghostscript or I must to use some another program?
If you want scaling applied to one axis and not the other, then you will have to do some PostScript programming. In /ghostpdl/Resource/Init/pdf_main.ps is the code which calculates the matrix required:
/pdf_PDF2PS_matrix { % <pdfpagedict> -- matrix
matrix currentmatrix matrix setmatrix exch
% stack: savedCTM <pdfpagedict>
dup get_any_box
% stack: savedCTM <pdfpagedict> /Trim|Crop|Art|MediaBox <Trim|Crop|Art|Media Box>
oforce_elems normrect_elems fix_empty_rect_elems 4 array astore
//systemdict /PDFFitPage known {
PDFDEBUG { (Fiting PDF to imageable area of the page.) = flush } if
That code calculates the x and y scale values and makes them the same. If you want them to differ, that's what you will have to modify. Note you will also have to set a specific media size using -dDEVICEHEIGHTPOINTS and -dDEVICEWIDTHPOINTS and set -dFIXEDMEDIA to prevent the PDF file resizing the media.
I have many scanned document in PDF.
I use ImageMagick with Ghostscript to convert PDF to PNG in big density. I use convert -density 288 2.pdf 2.png. After that I read the pixels with PHP and find where is QR code and decode it. Because image is very big (~ 2500px), it's need very much RAM. I want, before I read pixels with PHP, to crop the image with ImageMagick and leave only that part with the QR code.
Can I detect the approximate location of QR code with ImageMagick, crop and leave only that part ?
Sample PDF
Converted PNG
Further Update
I see your discussion with Kurt about better extraction of the image from the PDF in the first place, and his recommendation was to use pdfimages. I just wanted to add that you won't find that if you do brew search pdfimages, but you actually need to use
brew install poppler
and then you get the pdfimages executable.
Updated Answer
If you change the tile size to 100x100 on the crop command and run this for the second PDF you supplied:
convert -density 288 pdf2.pdf -crop 100x100 tile%04d.png
and then use the same entropy analysis command
convert -format "%[entropy]:%X%Y:%f\n" tile*.png info: | sort -n
...
...
0.84432:+600+3100:tile0750.png
0.846019:+600+2800:tile0678.png
0.980938:+700+400:tile0103.png
0.984906:+700+500:tile0127.png
0.988808:+600+400:tile0102.png
0.998365:+600+500:tile0126.png
The last 4 listed tiles are
Likewise for the other PDF file you supplied, you get
0.863498:+1900+500:tile0139.png
0.954581:+2000+500:tile0140.png
0.974077:+1900+600:tile0163.png
0.97671:+2000+600:tile0164.png
which means these tiles
I would think that should help you pretty much approximately locate the QR code.
Original Answer
This is not all that scientific, but it may help you get started. The key, I think, is the entropy of the various areas of the image. The QR code has a lot of information encoded in a small area so it should have high entropy. So, I use ImageMagick to split the image into square 400x400 tiles like this:
convert image.png -crop 400x400 tile%03d.png
which gives me 54 tiles. Then I calculate the entropy of each of the tiles and sort them by increasing entropy, also outputting their offsets from the top left of the frame, and their name, like this:
convert -format "%[entropy]:%X%Y:%f\n" tile*.png info: | sort -n
0.00408949:+1200+2800:tile045.png
0.00473755:+1600+2800:tile046.png
0.00944815:+800+2800:tile044.png
0.0142171:+1200+3200:tile051.png
0.0143607:+1600+3200:tile052.png
0.0341039:+400+2800:tile043.png
0.0349564:+800+3200:tile050.png
0.0359226:+800+0:tile002.png
0.0549334:+800+400:tile008.png
0.0556793:+400+3200:tile049.png
0.0589632:+400+0:tile001.png
0.0649078:+1200+0:tile003.png
0.10811:+1200+400:tile009.png
0.116287:+2000+3200:tile053.png
0.120092:+800+800:tile014.png
0.12454:+0+2800:tile042.png
0.125963:+1600+0:tile004.png
0.128795:+800+1200:tile020.png
0.133506:+0+400:tile006.png
0.139894:+1600+400:tile010.png
0.143205:+2000+2800:tile047.png
0.144552:+400+2400:tile037.png
0.153143:+0+0:tile000.png
0.154167:+400+400:tile007.png
0.173786:+0+2400:tile036.png
0.17545:+400+1600:tile025.png
0.193964:+2000+400:tile011.png
0.209993:+0+3200:tile048.png
0.211954:+1200+800:tile015.png
0.215337:+400+2000:tile031.png
0.218159:+800+1600:tile026.png
0.230095:+2000+1200:tile023.png
0.237791:+2000+0:tile005.png
0.239336:+2000+1600:tile029.png
0.24275:+800+2400:tile038.png
0.244751:+0+2000:tile030.png
0.254958:+800+2000:tile032.png
0.271722:+2000+2000:tile035.png
0.275329:+0+1600:tile024.png
0.278992:+2000+800:tile017.png
0.282241:+400+1200:tile019.png
0.285228:+1200+1200:tile021.png
0.290524:+400+800:tile013.png
0.320734:+0+800:tile012.png
0.330168:+1600+2000:tile034.png
0.360795:+1200+2000:tile033.png
0.391519:+0+1200:tile018.png
0.421396:+1200+1600:tile027.png
0.421421:+2000+2400:tile041.png
0.421696:+1600+2400:tile040.png
0.486866:+1600+1600:tile028.png
0.489479:+1600+800:tile016.png
0.611449:+1600+1200:tile022.png
0.674079:+1200+2400:tile039.png
and, hey presto, the last one listed (i.e. the one with the highest entropy) tile039.png is this one.
I have drawn a rectangle around its location using this command
convert image.png -stroke red -fill none -strokewidth 3 -draw "rectangle 1200,2400 1600,2800" a.jpg
I concede there may be luck involved, but I only have one image to test my mad theories. You may need to tile twice, the second time with an x-offset and y-offset of half a tile width, so that you don't cut the QR code and split it across 2 tiles. You may need different size tiles for different size barcodes. You may need to consider the last 3-5 tiles located for your next algorithm. But I think it could form the basis of a method.
This question is related to
Script (or some other means) to convert RGB to CMYK in PDF?
however way more specific. Consider that I am not an expert in print production ;)
Situation: For printing I am only allowed to use two colors, Cyan and Black. The printery requests the final PDF to be in DeviceCMYK with only the Channels C and K used.
pdflatex automatically does that (with the xcolor package) for all fonts and drawn objects, however I have more than 100 sketches/figures in PDF format which are embedded in the manuscript. Due to an admittedly badly designed workflow (late realization that Inkscape cannot export CMYK PDFs), all these figures were created in Inkscape, and thus are RGB PDFs.
However, the only used colors within Inkscape were RGB complements of CMY(K), e.g. 100% Cyan is (0,255,255) RGB and 50% K is (127,127,127) etc.
Problem: I need to convert all these PDF figures from RGB to DeviceCMYK (or alternatively the whole PDF of the final manuscript) with a specific conversion formula.
I did a lot of google research and tried the often suggested ways of using e.g. Ghostscript or various print production tools in Adobe Acrobat, however all of the conversion techniques I found so far wanted to use ICC color profiles or used some other conversion strategy which filled the channels MY and spared some C and K, for example.
I know the exact conversion formula for the raw color numbers from our Inkscape-RGBs to the channels C and K, however I do not know or find any program or tool that allows me to manually specify conversion formulas.
Question: Is there any workflow to convert my PDFs from RGB to C(MY)K manually with my own specific conversion formula for the raw numbers with the converted PDF being in DeviceCMYK using a tool, script or Adobe product?
Due to the large number of figures I would prefer a batched solution which doesn't require too much coding from my side, but if it should be the only solution, I'd also be open minded for a workflow like "load/convert/save" within a program for every single figure or writing a small program with an easy-to-handle C++ PDF API for example.
Limitations and additional info: A different file format (like TikZ figures) is not possible any more since it does not work perfectly and the necessary adaptions to the figures would create too much overhead. A maybe helpful information: Since the figures are created in Inkscape, there are no raster images within the PDFs. I also do not want all figures to be converted to raster images during the color conversion.
Edit:
I have created an example of a RGB PDF-figure created with inkscape.
I also did a manual object-by-object color conversion to a CMYK-PDF with Illustrator, to show how the result should look like. Illustrator stores the axial shading in a DeviceN colorspace with the colors cyan and black, which is close enough^^
Here is an idea, I think it will work if your PDF files are using exclusively the colorspaces DeviceGray, DeviceRGB and DeviceCMYK:
1- Convert all your PDF files to Postscript (with pdf2ps from ghostscript for example)
2- Write a Postscript program that redefines the operators setrgbcolor, setgray and setcolor with your own implementation in the Postscript language, your implementation will internally use setcmykcolor and it will compute the values using your custom formula.
Here is an example for redefining the setgray operator:
% The operator setcmykcolor expects 4 values in the stack
% When setgray is called, we can expect to have 1 value in the stack, we will
% use it for the black component of cmyk by adding 3 zeros and rolling the
% top 4 elements of the stack 3 times
/setgray { 0 0 0 4 3 roll setcmykcolor } bind def
3- Paste your Postcript program at the begining of each resulting ps file from step 1.
4- Convert all your files back to PDF (with ps2pdf for example)
See it in action by saving this piece of code as sample.ps:
/setgray { 0 0 0 4 3 roll setcmykcolor } bind def
0.5 setgray
0 0 moveto
600 600 lineto
stroke
showpage
Convert it to PDF with ghostscript using this command line (I used version 9.14):
gswin64c.exe -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=sample.pdf sample.ps
The resulting PDF will have the following page content:
q 0.1 0 0 0.1 0 0 cm
/R7 gs
10 w
% The K operator is the PDF equivalent of setcmykcolor in postscript
0 0 0 0.5 K
0 0 m
3000 3000 l
S
Q
As you can see, the ps-> pdf conversion will preserve the cmky colors specified in postscript with the setcmykcolor operator.
Maybe you can post your formula as a new question and someone could help you out translating it to postscript.
Since you have access to Illustrator, you might want to try importing the PDF into Illustrator and using Illustrator's scripting capabilities to iterate over the elements and replace fill/stroke RGB colors with their CMYK replacement colors.
The difficulty will be with the shading patterns (Gradients) used in the PDF; if they are imported as GradientColor, then in theory it's a matter of digging into the GradientColor to find the base RGB colors and substitute their CMYK replacement.
A very similar problem was solved using the ActivePDF.dll with C++ (or C#??).
i want to shrink png or jpg on OSX. i only want to shrinkg without affecting the image quality.
like tinypng.org
is there any recommended library? i just know imagemagick. is there a way to do that natively? or another library to shrink/compress images without affecting the image quality?
my aim is to shrink the file size, for example:
logo.png >> 476 k before shrink
logo.png >> 50k after shrink
Edit: to be clear, i want to compress the size of the file, not the image resolution.
TinyPNG.org works by using image quantisation - the similar colours in the image are converted into a HSV or RGB model and then merged depending on the distance.
How does it work?
...
When you upload a PNG (Portable Network Graphics) file, similar colours in your image are combined. This technique is called “quantisation”
...
src: http://tinypng.org
An answer here outlines a method of doing so: https://stackoverflow.com/a/492230/556479.
There are also some answers on this question with refer to how you can do so on Mac OS using objective-c: How do I reduce a bitmap to a known set of RGB colours
See Wikipedia for a more in depth guide: http://en.wikipedia.org/wiki/Color_quantization
Did you have a problem using ImageMagick? It has a rich set of quantize functions such as
bool MagickQuantizeImage( MagickWand mgck_wnd,
float number_colors,
int colorspace_type,
float treedepth,
bool dither,
bool measure_error )
Here is a very thorough guide to quantization using imageMagick
My suggestion is to use http://pngnq.sourceforge.net, it will give better results than ImageMagick and for the single example given in http://tinypng.org, it also produces a very similar output. It is a tiny C implementation of the method present in the paper "Kohonen Neural Networks for Optimal Colour Quantization". That alone is much better since you are no longer relying on closed unknown implementations.
Original (57 KB), tinypng.org (16 KB), pngnq (17 KB):
Using ImageMagick, the best quantization to 256 colors I can get uses the LAB colorspace and dithering by Floyd-Steinberg:
convert input.png -quantize LAB -dither FloydSteinberg -colors 256 output.png
This produces a 16 KB png, but it contains much more visual artifacts: