I would like to check image size without downloading it (images are located on servers), is it possible? I found that great class http://www.anttikupila.com/flash/getting-jpg-dimensions-with-as3-without-loading-the-entire-file/ but its only for JPEG, and It would be nice to have something for png as well. That class was written 5 years ago, so was there created anything like that and/or for other kinds of images, since then? I searched google without luck.
Christophe Herreman claimed that he wrote something like this for PNG but after inspection - it's something essentially different.
You may start to load the file, read the bytes at the beginning of the file, get the dimensions from there and stop loading. Here is the PNG format specification. After 8 bytes of signature, you may find what you need.
Related
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..
Am using GhostScript.Net 1.2.0 version. Am converting a pdf file into list of images to print. My Printed image height and width is fine but the printed image quality is poor. Please help me how to improve the image quality while converting a pdf to image using ghostscript.net
You need to either take this up with the Ghostscript.Net maintainer or find some way to tell us what command line/configuration you are using (ALL of it!), you will also need to supply an example file and define what you find objectionable in your current prints. 'image quality is poor' is extremely subjective, not helpful at all, there could be many, many reasons for 'poor quality', starting with your input file.
You also need to state what operating system you are using, and what your printing setup is. If you have tried anything already, then you need to say what you have done or we will waste much time suggesting dead ends.
Note that if you are using the mswinpr2 device, there may be little that can be done as that relies on the printer driver in the Windows system to do the actual printing.
It's my first experience with tesseract, I'm trying to read the digits contained in these tiff images:
http://imageshack.us/g/703/64553021.png/
As you can see they are in the same format and also same width/height. I don't know why tesseract returns the correct output only for the second image ("150") instead for the first one returns a blank output.
Maybe I should modify them to best fit tesseract? How? I can use Imagemagick if needed.
Thanks in advance.
In the readme they say:
In the executable, page layout analysis is enabled by default. You may need to turn it off to process small images. No command-line control for this yet. Sorry. See tesseractmain.cpp.
I think your images are too small, try editing the code (and recompile).
This may well be a little of an open-ended question
The site I am working on requires to be optimised for performance. One of the key areas is to optimise the file sizes of the images used upon the site.
Unfortunatley these images are being created by employees who do not have the required knowledge for creating images for the web, and it is my job to produce a set of guidelines for them to use.
I was wondering whether there was any resource/guidlines/literature regarding typical images file sizes for images of different dimensions - as I would like to include something like this to aid them to ensure their images are being created properly.
Any info would be greatly appreciated.
Thanks in advance
I can't answer the opinion question, but I can suggest some guidelines that will keep your images smaller.
First off, if they're using Photoshop to edit their images, it's likely they're storing a whole bunch of crap in the headers (digital papertrail, EXIF data, and such). Also, folks will frequently save in too high a bit depth.
For novice users, trying to explain why they need to use "save for web" is more likely to confuse them. Instead, just point them at:
http://www.smushit.com/ysmush.it/
This site is rather handy - it will compress all the images on a page you specify, or you can upload the images.
You should strongly consider writing some guidelines about where images are stored as well. It's frequently very beneficial to have your static image content stored on several servers, apart from your dynamic content. Most browsers will only download a limited # of files at a time from any given website (usually it's 2).
Unless there's a good reason, all your images should be cached using one of the HTTP cache techniques (expires, etags, etc).
Good luck.
72 dpi as a resolution and either jpeg or png formats work best.
Try to use images at the exact pixel area size they will end up being displayed as. This is specified by the images height and width attributes.
You can set the output quality of a jpeg image which will also save file size although there is a trade off against image quality.
I hope this is of use.
We would like to display very large (50mb plus) images in Internet Explorer. We would like to avoid compression as compression algorithms are not what CSI would have us believe that they are and the resulting files are too lossy.
As a result, we have come up with two options: Silverlight Deep Zoom or a Flash based solution (such as Zoomify). The issue is that both of these require conversion to a tiled output and/or conversion to a specific file type (Zoomify supports a single proprietary file type, PFF).
What we are wondering is if a solution exists which will allow us to view the image without a conversion before hand.
PS: I know that you can write an application to tile the images (as needed or after the load process) and output them; however, we would like to do this without chopping up the file.
The tiled approach really is the right way to do it.
Your users don't want to download a 50mb file before they can start viewing the image. You don't want to spend the bandwidth to serve 50 megs to every user who might only view a fraction of your image.
If you serve the whole file, users will eventually be able to load and view it, but it won't run smoothly for most of them.
There is no simple non-tiled way to serve just a portion of an image unless you want to use a server-side library like imagemagik or PIL to extract a specific subset of the image for each user. You probably don't want to do that because it will place a significant load on your server.
Alternatively, you might use something like google's map tool to provide zooming and scaling. Some comments on doing that are available here:
http://webtide.wordpress.com/2008/08/27/custom-google-maps/
Take a look at OpenSeadragon. To make a image can work with OpenSeadragon, you should generate a zoomable image format which mentioned here. Then follow starting guide here
The browser isn't going to smoothly load a 50 meg file; if you don't chop it up, there's no reasonable way to make it not lag.
If you dont want to tile, you could have the server open the file and render a screen sized view of the image for display in the browser at the particular zoom resolution requested. This way you arent sending 50 meg files across the line when someone only wants to get an overview of the image. That is, the browser requests a set of coordinates and an output size in pixels, the server opens the larger image and creates a smaller image that fits the desired view, and sends that back to the web browser.
As far as compression, you say its too lossy, but if thats what you are seeing you are probably using the wrong compression algorithm or setting for the type of image you have. The jpg format has quality settings to control lossiness, and PNG compression is lossless (the pixels you get after decompressing are the exact values you had prior to compression). So consider changing what you are using as compression, and dont just rely on the default settings in an image editor.