I'm trying to make a DataMatrix reader in javascript that can process an image and extract the information in there. The problem is with detecting the square inside the image with the datamatrix, as this can vary in location and orientation. The input image looks like this:
I want to find and extract only that part (square) of the image that shows the datamatrix, from there on out I have the processing/decoding covered. The desired result for the image above would be:
I need this picture as an ImageData array of some kind, so that I can use that as input for further processing. I am stuck as to how to approach this, how to get the image orientated correctly and the right subsection of the image selected. Is there anyone who has some suggestions/solutions on how to approach this?
Thanks in advance!
Related
I am attempting to upload an image by capturing from camera on android phone. After searching why the image shows rotated I found the reason was due to the image EXIF of the captured image. And I was wondering what is the best practice to rotating the image back to normal, is it after uploading the image or when viewing the image?
Also I need assistance in writing the JavaScript code for that given that I have an image element and file input element.
I love the circular profile pictures, but I hate that you cant edit them. Say for example you dont want the circle in the middle and the standard size, but you want it smaller or something.
Explanation with pictures:
The 4 images, from bottom to top: input, image editor, moving circle, output
Now, I want that you put a normal image in and that there will be a black overlay with some kind of opacity. In the middle you'll have a transparent circle so you can select the part you want in the circle. Then you can press save and there will be a .png file made.
I was thinking of doing this with jQuery watermarks, but I couldn't figure it out. Anyone got a idea?
There are a couple of methods:
You can use CSS2/3 - with corner-radius (for newer browsers) or even just an overlay image, image can be cropped, and background can be scaled/moved via CSS background-position and background-size accordingly. To save the image, you'll need a minimalistic PHP script do do the same operation server-side (given the parameters) and output the image to user.
You can also use HTML5 canvas - specification involves a handy clip method (which is straightforward - limits drawn imagery to current path), and you can obtain the image data via toDataURL method of canvas element as long as image is uploaded to the same server (or cross-domain rules are done right). A minimal search on saving files from JS+HTML5 should further assist.
Sample jsfiddle - http://jsfiddle.net/u2A7t/
I would like to implement an image collage, where the photos are arranged on the page within a 'Word' object.
This is really hard to explain, this maybe why I haven't found any examples on the web. But as an example, let's take the word 'HTML'.
I would like to create a shape on a canvas on the screen, and then have photos transition onto the screen (easing, sliding, flying) and then arranging themselves sporadically around that shape. Then have the images clickable/zoomable. If possible, draggable as well within the shape.
Now, my first question, is this achievable, and how would I go about doing something like this?
I don't know too much surrounding HTML5 canvas, and am using this project to get my teeth into it. So I would really like to know briefly how something like this could be done.
thanks!
You can do something like a mask in photoshop you would get an image with invisible area with the shape you want to mark and then put the world image in the background.
This might also be of help http://www.html5rocks.com/en/tutorials/masking/adobe/
I am learning to develop mobile applications, quite in the initial phase.
This query is not related to mobile but more to html/css/js.(for
I intend to make a simple game, where a picture is seen, a few options are available and the user can drag and drop these options onto the image.
eg. There is an image of a plant > options are #leaf #stem #flower #bud
The user must drag and drop the correct option to the correct place on the image to get points. i.e Drag the #leaf option onto the leaf of the plant.
Now my problem is the image, the separation of these points, I can't figure out how to do it.
Query in short: How do I access separate points/sections on a single image in html/js for above purpose?
Query (longer version)
I did a little search and realised I can slice the image and recreate it using multiple images, I tried this, it sort of works but it has a a lot of drawbacks:
1)More images mean more space, combined size of the split images was about 1.5x the original image(this is just splitting it into 4 images)
2)For a complex picture, the number of images to slice into is large and hard to manage in css(n00b==me) as they don't just need to be split into a simple X*Y grid but a much more complex split depending on the object in the image.(realised when I was trying to do a simple cell structure img)
3)More images also means more http requests(in case the app is WebView based) which will increase loading time.
It just seemed liked too much of a hassle, there must be a better way.
Then I saw css sprites , I dont need to combine my images like sprites are intended for, rather the reverse. Just access parts of my pre-existing image, as separate objects.I haven't tried this(working on it) and and I haven't seen this being done either, or maybe its being done and I'm not seeing.
Please help guys, my problem is quite simple(I think) , I think I'm just not getting the correct google search terms.
If anybody has any ideas,links, resources and also any clarifications as I may not have put up my problem as clearly as I'd like to, please do reply.
regards,
Rahul Agarwal
You could try to place transparent divs over the main image using absolute position and fixed dimensions. Those divs will be assosiated to the possible options, and when a user drops an option over some specific div, you'll know what points to give.
Little demo using two divs and an animated scaling to show that the positioned divs will scale according to their parent:
http://jsfiddle.net/VK3A8/
fiddel with image:
http://jsfiddle.net/8qLFc/4/
I'm to take an image on a webpage, and then use javascript (or whatever would be best suited) to dynamically 'pixelate' it (e.g. into 20px squares). Then, as the user scrolls down the page, I need the image to gradually increase in resolution, till it is no longer pixelated.
Any ideas how I could go about doing this? I realise I could use php to resize an image and several times and just switch out the image, but that would require loading several extra images. Also, I know I could probably do the effect with flash & pixelbender, but I want to achieve it within the limitations of HTML5, CSS & Javascript if possible.
Appreciate any thoughts!
Update: Something like this, but with Javascript instead of Flash? http://www.reflektions.com/miniml/template_permalink.asp?id=390
You could render the picture in a hidden <canvas> element. Then use a derivation of the technique described here http://dev.opera.com/articles/view/html-5-canvas-the-basics/#pixelbasedmanipulation . To create a pixelated version of the image in a second <canvas> element using ever decreasing fillRect's. This way you even buffer the orginal image data.
edit: I would use 2 <canvas> elements so that you only have to fetch and draw the original image once. Perhaps you could buffer/cache this image in the same <canvas> element but by drawing it outside of the view port i am not sure if this is possible though.
I would use a calculation where you get the width in pixels divided by the square width and then the height divided by the square height. This would give you the lower resolution your looking for.
Then you can find a way to change the resolution to the result or grab the color of every pixel at position (height and width)/2 of the square your looking for. Then generate them into div tags or table with the appropriate color and size eventually resulting in the image its self.
I have a probably faster idea where you can have multiple versions of the image and change their z-index or their visibility as you scroll. Basically each image would have the different resolutions. If you have to do that to many images then this solution wont be as efficient as there would be lots of image editing but you can always do a batch edit.
Let me see If I can think of more ideas then I will edit.
Have a look at http://close-pixelate.desandro.com/
Explanation here: https://stackoverflow.com/a/8372981/22470
Not in a portable way.
That might be doable in Flash. Firefox JS extensions allow it to read images as JS arrays, Base64 strings etc. You might experiment with "1 DIV=1 pixel" hack, but it's hard to get any reasonable size of the image at any reasonable speed. If you feel really hyper, you could try creating base64-encoded images on the fly using the data: URI... many ways but none good...