Load a image.png in a few milliseconds

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I need to perform a function on images in less than 1 second. I have a problem on a 1000x1000 image that, just to load it as a matrix in the program, takes 1 second.

The function I use to load it is as follows:

import png

def load(fname):

    with open(fname, mode='rb') as f:
        reader = png.Reader(file=f)
        w, h, png_img, _ = reader.asRGB8()
        img = []
        for line in png_img:
            l = []
            for i in range(0, len(line), 3):
                l+=[(line[i], line[i+1], line[i+2])]
            img+=[l]

        return img

How can I modify it in such a way that, when opening the image, it takes a little more than a few milliseconds?

IMPORTANT NOTE: I cannot import other functions outside of this (this is a university exercise and therefore there are rules -.-). So I have to get one myself

Appending to a list is inherently slow - read about Shlemiel the painter’s algorithm. You can replace it with a generator expression and slicing.

    for line in png_img:
        img += list(zip(line[0::3], line[1::3], line[2::3])

Getting Started with Images — OpenCV-Python Tutorials 1 , IMREAD_UNCHANGED : Loads image as such including alpha channel. Note. Instead of these three flags, The function waits for specified milliseconds for any keyboard event. If you press any key in that time, the This will save the image in PNG format in the working directory. Some, we will see on the way. Warning. EDIT: I have already used NSTimer, so that image is hidden for some milliseconds, but as i told I placed that image in window file, it displays at the beginning of the page loading, dont know wat to do. Please help.

you can use PIL to do this for you, it's highly optimized and fast

from PIL import Image

def load(path):
    return Image.open(path)

5 ways to load website images faster, Instantly load your images faster with Sirv. Be sure to serve your images in the most appropriate format: JPEG, PNG or WebP. HTTPS requires a few extra milliseconds before images are displayed because, unlike HTTP, requests require� Load using keras.preprocessing. Let's load these images off disk using image_dataset_from_directory. Note: The Keras Preprocesing utilities and layers introduced in this section are currently experimental and may change. Create a dataset. Define some parameters for the loader: batch_size = 32 img_height = 180 img_width = 180

I'm not sure it is remotely possible to run a python script that opens a file, etc. in just a few ms. On my computer, the simplest program takes several 10ms

Without knowing more about the specifics of your problem and the reasons for your constraint, it is hard to answer. You should consider what you are trying to do, in the context of the way your program really works, and then formulate a strategy to achieve your goal.

The total context here is, you're asking the computer to:

  1. run python, load your code and interpret it
  2. load any modules you want to use
  3. find your image file and read it from disk
  4. give those bytes some meaning as an image abstraction - parse, etc these bytes
  5. do some kind of transform or "work" on the image
  6. export your result in some way

You need to figure out which of those steps is it that really needs to be lightning fast. After that, maybe someone can make a suggestion.

How to optimize image loading on your website, I often see websites that load several megabytes worth of images just to have a This reduction in size results in a load time of 550 milliseconds instead once the image has been changed, we can do some awesome CSS� Then a few milliseconds later the page jumps to show this: --------hr-------- [ ] [ image ] [ ] text Is there a simple way that I can show a grey background image of exactly the width and height that the image will occupy, until the image itself loads?

The Complete Guide to Lazy Loading Images, In this guide, we will cover all of the ins and outs of lazy loading images, the load, the user may wind up waiting a few milliseconds longer for the image to� This is a good technique to reduce the over all time it takes to load the gallery, but it means that the time to load the most important image, the next one, is significantly longer because it is competing for bandwidth with the other simultaneous requests. On a moderately slow 1.5Mbps DSL connection, a 350k image can take 2 seconds to load.

Lazy Loading Images – The Complete Guide, combined with the fact that the load image for a few milliseconds while the image loads up. How-To: OpenCV Load an Image. The objective of this post is to show you how to read an image off of disk using OpenCV, display it on your screen, and then wait for a key press to close the window and terminate the script.

How-To: OpenCV Load an Image, How do I use OpenCV to load an image and display it on my screen? A few well placed calls to cv2.imshow will quickly help you resolve the problem. waitKey takes is an integer, which is a delay in milliseconds. I have a problem of loading .png image with transparency channel – I could do it with PIL� 2 Loading and saving images. Use load.image and save.image. imager supports PNG, JPEG and BMP natively. If you need to access images in other formats you’ll need to install ImageMagick.

Comments
  • Does this answer your question? OpenCV Python: fast solution for 3-channel float32 image reading?
  • Are there functions in Reader other than asRGB8 that you could call that might be faster?
  • I do not know this. I have, however, double-checked the code and the problem is the for loop
  • It's not just one for loop, it's two of them nested. That's an O(n^2) problem which will always be slow.
  • Question stipulates a requirement of a few milliseconds, but does not clarify. I don't think they know what a millisecond is. This is actually a pretty specific requirement, but seems to be used casually. Question is as a result very unclear
  • Thank you for your suggestion. The problem is that this is a university exercise and I was ordered not to import other libraries than the ones they gave me. I have to find a way to do it with what I have and at the moment I only have this 'load' function that they gave me. But this function for the times I have to respect is not good and I have to write one myself. Can you give me some other suggestions?