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.
Related
I'm trying to insert some SVG images in a PDF using TCPDF with the method TCPDF::ImageSVG, but when I try this I get a white space.
If I try to enable TCPDF::setRasterizeVectorImages the image shows in the PDF file, but it is rasterized of course and so its quality is not good.
Do you have any idea?
Thank you very much for your help!
Unfortunately, TCPDF's SVG handling is quite limited, and the cause of your issue depends on the SVG you are trying to use. Later versions of TCPDF support more SVG functionality, so if you haven't done so, try using a later version of TCPDF.
If an update doesn't resolve the issue, and you're forced to use raster images, you can improve quality at the cost of file size. You can do this by rasterizing them at a high DPI yourself outside of TCPDF. Once you've done this, take your new high-resolution raster image and add it to your PDF with the Image method like any other raster image. At work we usually rasterize to 300dpi, but your application may call for more or less.
If your image gets added to the PDF far larger on the page than you expected, specify at least one of the dimensions so TCPDF knows how much of the page you're intending the image to use.
I'm evaluating Fine Uploader compared to various other options, specifically JQuery File Upload.
I generally prefer the Fine Uploader approach as it's more lightweight, compared to JQuery File Uploader which has dependencies on Bootstrap and JQuery UI.
However it's important to be able to resize images: e.g., a user may select a large file from their camera and this may be very large - uploading the full resolution photo may take a very long time. JQuery File Upload doe this.
Additionally we don't have much use for very high resolution files.
If possible (I'm aware some browsers may not support this), I'd like to be able to resize images client size.
Is this possible?
Fine Uploader does not currently have any native support for image manipulation. This is a feature in our backlog, but we have not had many users tell us they are interested in this. This is one of the reasons why such a feature has yet to be implemented natively. There is a case, #707 that marks the start of native image-editing support for Fine Uploader. It is tentatively scheduled for 4.0.
However, you can certainly make use of FileReader and Canvas to resize the image. You can then submit this resized image as a Blob to Fine Uploader via the addFiles API method. At that point, the file has been submitted and Fine Uploader is ready to upload the item.
Essentially, the steps you would follow to handle this specific scenario, before Fine Uploader natively supports image manipulation:
Provide your own file input element(s) or make use of Fine Uploader's file/folder drag and drop support to get a handle on some files selected by the user.
Use FileReader to read the contents of the image.
FileReader will provide you with a URL for the image, assign that to the src attribute of an img element.
Draw the img onto a canvas element. This is where the resizing occurs.
Grab the URL of the resized image from the canvas element (canvas.toDataURL(...)).
Convert the URL to a Blob.
Pass the Blob to the addFiles API method of Fine Uploader.
The intent is to take care of most if not all of this for integrators such as yourself in the future by adding native image manipulation support to Fine Uploader.
Hope this helps.
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 want to use Webp and get my images much small, at last for serving them to chrome browsers. I've download many types of conversion tools, including the official one. I tried to convert PNG with Alpha transparency and get awful results. See image below..
According to what I see on many websites, it shold handle transparency incredibly well. I wanted to know if you know why I get these kind of results and what I need to do or what tool I need to produce high quality webp transparent images that will replace my png ones.
Second, I wanted to know the comparability. Should I server those images only for chrome uses? - OF course the most important issue is the image quality outpu.
Thanks
You are probably using an older version of WebP library/binary, which didn't have alpha support. So the images you see have alpha channel stripped.
Try again with the latest release v0.2.0:
http://code.google.com/p/webp/downloads/list
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.