Currently, my app creates GeoTiff tiled files using following options:
PROFILE=GeoTIFF
TILED=YES
BLOCKXSIZE=xxx
BLOCKYSIZE=xxx
COMPRESS=JPEG
PHOTOMETRIC=YCBCR
JPEG_QUALITY=xx
However, some apps that use my served tiles do not work due to "invalid" JFIF format.
How can I force gdal to ensure JFIF format in GeoTiff tiles?
See my own answer in https://gis.stackexchange.com/questions/426732/generate-jpeg-ycbcr-tiles-in-geotiff-file-with-jfif-format-instead-pure-jpeg-for/428023#428023.
Basically, solution involves gdal code modifications
Related
I am trying to add three.js based 3D objects to a PDF page. It seems there are no direct exporters available to do that. So I am trying to do the below thing,
Convert the gltf/stl/obj files to U3D files
Add the .u3d file to PDF page.
I am trying to do the below process and I am not sure whether this approach is possible. It will be a great help if there is any support available to do any one of the below conversions. Also if you know any other possible approaches, kindly update me!!
Input formats output format
GLTF
OBJ U3D
STL
(any
three.js supported
3D formats)
Thanks.
There are few options available to export the three.js graphics to a PDF ( static content not a dynamic U3D assets)
Static contents
Get the rendered data from the three.js webGL renderer / canvas renderer using toDataURL("image/jpeg"), change the MIME type to JPG/PNG and add the resulting stream as an image to PDF ( this worked for me)
example - https://plnkr.co/edit/Ty8BZaDcflCJH5tH?preview
Like the above approach we can use three.js svgrenderer to export the renderer contents into a SVG data stream, which can be added into the PDF ( textures, mesh may not be 100% reproduced)
The legacy API - "threejs-pdf-renderer" can be used to directly export the three.js animations to a PDF. We don't need any other dependencies to create the PDF. But this is a legacy API which uses legacy three.js version, lot of effort needs to be done to make the API to be compatible with the latest three.js version.
example - https://satheeshks10.github.io/ThreejsPDFGenerator/
Dynamic 3D contents
We can export the three.js animations into a U3D file (no direct support is available as for now), this U3D file can be directly embedded into PDF.
example - https://tetra4d.com/pdf-samples/
I have found many answers about converting .svg files to rasterized formats, however I would prefer to keep it as a single svg file. I got excited when I found react-native-svg, but was then disappointed when I saw their image example used a .jpg file.
Is keeping my image as a vector possible? Am I trying to do something unwise?
Thank you for your help.
You need to convert your SVG's to use the react-native-svg library, this is a useful tool to do so: https://react-svgr.com/playground/
This does not rasterise the image, it will remain as a vector just in a format that the library can parse.
With phantomjs you can choose the file format to use for page.render().
I'm finding that the file size I'm getting for png is around three times higher than what I'm getting for gif. I wasn't aware that png should be any worse (in terms of file size) than gif; in fact I thought png was meant to be better.
Unfortunately, I kinda need to output to png because of its support for variable opacity, but the larger file size is a bit of an issue.
So, is there any way in which I can control file size of the png? Maybe change the encoding scheme or something? I'm currently using phantomjs 1.9.8.
Inside of PhantomJS
No, there is no way to make the png file size smaller, but there is a way to make it bigger (just for fun):
Render the file to png,
load the file to a canvas of appropriate size,
get the Data-URI of the canvas in png or any other format,
decode the Base 64 part and write to file (this is very tricky to get right).
PhantomJS 1.x has a bug which results in a vastly inflated, but valid file.
Only jpeg rendering enables you to specify a quality setting which will result in a smaller file size, but then again jpeg doesn't support transparency.
You could also see whether PhantomJS 2.0.0 behaves better, because it has an engine underneath it that is almost three years newer than in PhantomJS 1.x.
Outside of PhantomJS
Your best bet would be to render the png in PhantomJS as-is and post-process it with your favorite library. It may even be enough to open it and save it again.
You can for example call an installed program with the child process module or your can open a webpage that contains such a service and upload the captured file or base64 representation of it. The possibilities are endless.
My use case is pretty simple. I need to convert the PDFs to images.I tried using apache pdfbox and i am having some trouble in converting pdfs which contains scanned images. when i convert scanned image the image clarity is lost due to compression/scaling. So i was trying to extract the image data from the PDF and then store it. But the problem is i may get PDF files which will contain images and text in which case i would need to fallback to image conversion mode. The problem is how to differentiate between the pages/documents having only image and the ones with composite data. I was thinking i could use ProcSet defenition for this purpose but looks like it is marked as obsolete and non-reliable according to PDF specifications. Other possibility is to check all the objects linked to that page and see if it contains anything other than images. Please let me know if there is an easier way of doing this
Thanks
If your intention is convert pdf to image, It is better to use ImageMagick for that. If you use ImageMagick, there is a lot options to change the quality of the image. And converting pdf to image is pretty simple using ImageMagick.
I'm trying to read JPEG2000 images in Magick++ (the C++ API of ImageMagick). To read an image I use the following code:
Image img("path/to/my/image.jp2");
But when I try to do this, ImageMagick throws an Exception and doesn´t load the image.
I extract the images out of PDF files. Could it be that something´s different to normal JPEG2000 images? To extract the images I read the stream of Image objects which have a JPXDecode-filter and save them to a file.
Hope someone can help me!
ImageMagick uses a package called JasPer to handle JPEG2000's. According to the wikipedia page on OpenJpeg, JasPer does not completely support the JPEG2000 specification. I have several extrected JPEG2000 that open fine in QuickTime, but fail to decode with ImageMagick.
I have had better results using OpenJpeg to decode the the Jpeg2000. The interface is less flexible, it will convert to PNG and BMP.