I was recently reading about progressive image loading, but I was disappointed with the fact that a separate thumbnail was being used for the initial "blurry" rendering, as this creates additional data for the client to download.
My understanding is that existing raster image formats are organized by coordinates (left to right, top to bottom). It seems to me that the image data could be ordered based on a downscaling algorithm. This would allow the client to automatically display a progressive representation of the image as it downloaded the data.
Are there any existing file formats and/or methods that allow progressive image loading without creating separate thumbnails for each step of resolution?
Did some more research. What I'm looking for is called interlacing.
Existing interlacing approaches aren't exactly what I had in mind, but it is definitely the same concept.
Related
Pretty much with every Pagespeed test I do for all my website I get the comment "Optimize images by lossless compressing image X" which often increases my page rank a lot.
I already save EVERY image with 'save for web' with Photoshop, but I was wondering how I could "Optimize images by compressing lossless" even more. As far as I know I'm already doing everything I can.
Really wondering..
Off-topic, but I noticed that Google's PageSpeed uses a Retina device to check, since all my Retina images got loaded instead of the regular ones. Since these are larger than the area I got a 1/100 score on the mobile segment. Haha.
This was a real issue with many of my sites, however I use the free version of kraken to 'loosely compress' all of my images and this passes the Google Test, thus boosting rankings!
https://kraken.io/web-interface
I must have used this for well over 10,000 images already!
The images you create in programs like Photoshop and Illustrator look amazing but often the file sizes are very large. This is because the images are made in a format that makes them easier to manipulate in different ways. If you put these files on your website it would be very slow to load. Optimizing your images for the web means saving or compiling your images in a web-friendly format depending on what the image contains.
How does it work?
There are two forms of compression that we need to understand, Lossy and Lossless.
Images saved in a lossy format will look slightly different than the original image when uncompressed. Keep in mind that this is only visible at a very close look. Lossy compression is good for web, because images use a small amount of memory, but can be sufficiently like the original image.
Images saved in lossless format retain all the information needed to produce the original image. For this reason, these images carry a lot more data and in return are a much large file size.
We also can optimize images for the web by saving them as the appropriate dimensions. Resizing the image on the webpage itself using CSS is helpful but the issue is the web browser will still download the entire original file, then resize it and display it.
Can you imagine taking a poster size image and using it as a thumbnail? The little 20px by 20px image would take as long to load as the original poster when we could just be loading a 20px image the whole time.
How to Optimize Images?
In simple terms optimizing your image works by removing all the unnecessary data that is saved within the image to reduce the file size of the image based on where it is being used in your website. Optimizing images for the web can reduce your total page load size by up to 80%.
Full optimization of images can be quite an art to perfect as there are such a wide variety of images you might be dealing with. Here are the most common ways to optimize your images for the web.
Reduce the white space around images – some developers use whitespace for padding which is a big no-no. Crop your images to remove any whitespace around the image and use CSS to provide padding.
Use proper file formats. If you have icons, bullets, or any graphics that don’t have too many colors use a format such as GIF and save the file with lower amounts of colors. If you have more detailed graphics then use JPG file format to save your images and reduce the quality.
Save your images in the proper dimensions. If you are having to use HTML or CSS to resize your images, stop right there. Save the image in the desired size to reduce the file size.
To resize your images you will have to use some form of program. For basic compression, you can use a simple editing program such as GIMP. For more advanced optimization you will have to save specific files in Photoshop, Illustrator, or Fireworks.
Assuming a simple product demo e.g. the one found on http://www.sublimetext.com/
i.e. something this isn't traditional high res video and could be reasonable accomplished with:
animated gif
video (can be embedded youtube, custom html5 player, whatever is most competitive)
canvas
The question is, which performs better for the user? Both in terms of:
The size of the files the user must be downloaded to view the 'product demo'
The requirements in terms of processing power to display the 'product demo'
If you feel that there's a superior technology to accomplish this or another metric to judge its usefulness, let me know and I'll adjust accordingly.
I know it's already answered, but as you specifically referred to the Sublime Text animation I assume you're wanting to create something similar?
If that's the case then here is a post explaining how it was created by the Sublime Text author, himself:
http://www.sublimetext.com/~jps/animated_gifs_the_hard_way.html
The interesting part of the article is how he reduces the file size - which I believe is your question.
With a simple animation such as the one at the link you're referring to, with a very low frame rate, a simple animated-PNG of animated GIF will probably be the best solution.
However, you need to consider band-width factor in this. If the final size of the GIF or the PNG is large then probably a buffered video is probably better.
This is because the whole gif/png file needs to be downloaded before it shows (I am not sure how interleaved PNGs works when they contain animation though).
A video may be larger in file size, but as it is typically buffered you will be able to show the animation almost right away.
Using external hosts such as YouTube or others can be beneficial to your site as well as the band-width is drawn from those site and not from your server (in case you use a provider that limits or charge for this in various ways).
For more information on animated PNGs or APNG (as this is not so well-known):
https://en.wikipedia.org/wiki/APNG
The canvas in this is only a displaying device and not really necessary (an image container does the same job and can also animate the GIF/PNG whereas a canvas cannot).
If you use a lot of vectors then canvas can be considered.
CSS3 animation is also an option for things such as presentation slides.
The problem:
We have large product images we want thumbnails of at various size but don't want to be stuck batch processing the images in Photoshop. We want a dynamic way or resizing images, that wont add an extra load time while the images is processing on the backend.
Amazon does this some how with their ecommerce solution. When you upload an image it resizes the image in square format and then gives you every size imagineable. ex 150x150, 149x149, etc. Starting at the largest size of the image, so if you upload a 1024x900 image it will resize it to 1023x899, 1023x1203 (add in white space where needed), then resize every pixel until it gets to 1x1px. The some how stores all the images to the server (if it even does that)
"there's got to be a better way"
Any suggestions on the best way to handle image resize on the fly?
Dynamic image processing can be incredibly fast, and it's a much better solution than generating every possible combination of sizes for an uploaded image.
The open-source ImageResizing.Net library allows dynamic crop/zoom and resizing, and with the WIC plugin can often have round-trip times of less than 20ms. That's hard to beat. It also offers disk caching and Amazon CloudFront & S3 support if you want to scale with the big folks. It's used by 20K-60K websites, and some servers host upwards of 20TB of images.
I'm pretty sure Amazon uses cached dynamic image resizing for their eCommerce solution. Pre-generating image versions is a very 2001-era solution.
[full disclosure: I'm the author.]
What is the best way to store images for web-sites?
What size I should not exceed?
Now, I save all interface-files in png (mostly in sprites) and usual images in jpg's. Some images are about 100-150Kb.
What quality and compression should I choose while saving images?
Preparing Images
To prepare images for presentation on
the Web, follow these steps:
Begin a new file. If it’s a photo or original artwork, use 300 dpi as
the resolution. If you are creating
something simple, set the resolution
to 72 dpi.
Use the drawing, text, shape and other tools provided in the graphics
program to create your image.
Save your file in the native file format (a file type meant for editing
that is specific to the image editing
program) of the program you are using.
For example, a Photoshop document
creates files with a ".psd" extension.
If you need to make a change or edit
later, do it in this file rather than
on the Web.
If necessary, lower the resolution of the image to 72 dpi.
If necessary, resize the image to the height and width in pixels
specifications desired.
Save the file in a Web-ready file format, usually a GIF (most programs
give you several choices for file
types), finding a balance between the
way the file looks and an appropriate
file size. Some image programs will
let you preview the final file output,
whie in others, you have to save it
and load it in the browser to see the
final effect.
Preparing Photographs
To prepare photographs for
presentation on the web, follow these
steps:
Download the photo from your digital
camera or scan in the photograph. The
process for this varies depending on
the software bundled with your scanner
or camera. The image will probably end
up in "Your Photos" on Windows, or the
"Photos" folder on a Mac, unless you
chose some other folder as the default
destination.
Use the color correction, drawing, text, shape, and other tools provided
in the graphics program to alter and
improve your image.
Save a copy of your file in the native file format of the program you
are using. Make later changes or edits
in this file rather than on the web.
With photographs, save an untouched
version of the photo in case you want
to use it again for another purpose.
If necessary, lower the resolution of the image to 72dpi.
If necessary, resize the image to the height and width in pixels
specifications desired.
Save the file in a web-ready format, usually a JPEG, finding a
balance between the way the file looks
and an appropriate file size.
Making images web-ready is all about
compromise. In general, the better
your image looks, the larger the file
size will be. The larger the file
size, the longer it will take to
download. Your job is to find a
compromise between quality and file
size. Some things to consider are:
Is this image conveying crucial information? If so, go for higher
quality.
Is the image on a page with a lot of other images? If so, make the file
size smaller.
Will your web visitor be able to detect that the quality of a photo or
image isn’t very good?
Make images of people fairly high quality because visual acuity is
strongest with people’s faces.
(Source)
For your images, here is a tip:
Do not scale images in HTML
Web page designers sometimes set image
dimensions by using the width and
height attributes of the HTML image
element. Avoid doing this since it can
result in images being larger than
needed. For example, if your page
requires image myimg.jpg which has
dimensions 240x720 but displays it
with dimensions 120x360 using the
width and height attributes, then the
browser will download an image that is
larger than necessary.
(Source, see another tip)
This all depends on what the image is for. If you're generally adhering to a web-safe palette, gifs will come out smaller and clearer than a jpeg. Jpeg's are for photos. For jpegs to handle websafe colors well, you need to save at 88%+ quality, which increases file size. Png's generally have the best quality, and in some cases (when you don't need transparency) can come out smaller than jpgs, and comparable to gif. So, for jpeg photos, 80 quality, (sometimes even 75 for smaller images) will get you decent results and small filesize. Use gifs / png for site imagery generally. As far as images on a page, I try not to exceed 30kb total, assuming the page isn't something that is focused on photos / imagery. Hope this helps.
It depends on what your image is of, and what the quality needs to be, whether you choose quality over page loading etc.
I personally save all mine in .png but IE has a problem rendering the colour correctly in .png so if you are using them for aestetical purposes I would save .jpg
As to the size of the image, like said it depends really on the quality you want your image and how it affects performance if it is a large file.
i usually use save for web mode that exists in photoshop. obviously the lower size is best. The sizes that you talking about (100-150) are good or not in relation to the dimension of the image. Anyway i advice you to use sprites and when possible in jpeg format.
something like 75-80% quality are good enought to a good quality of image
And please pay attention to the cmyk mode, that cause problems in some browsers
I am working on an iPad application which has hundreds of photo-quality images. I would have naturally assumed to store these images as JPEGs so as to optimize the app file size. However, Apple's guidelines state:
Use the PNG format for images. The PNG format provides lossless image content, meaning that saving image data to a PNG format and then reading it back results in the exact same pixel values. PNG also has an optimized storage format designed for faster reading of the image data. It is the preferred image format for iOS.
However, if I store the same images as JPEGs at 100% quality, the size of them drops to about half that of the PNG lossless versions.
Is there really that much of a performance hit to use JPEG instead of PNG? If I am viewing these images in a carousel or gallery style, do I really need to worry about the performance and use PNGs instead?
Thanks!
Regarding the quality PNG is good for application kind of images, but JPEG is preferred for photos. Choose the lowest JPEG quality that gives good enough quality for your images.
Regarding speed, size also matters. I have no IPad to test with, but the smaller file size to read from flash or network might very well out weight any additional decompression cost. The only way to find out is to measure on your actual device.
There is a performance consideration but while PNG is preferred for quality, given your application, I'd suggest JPEG would be preferable.
Pure performance isn't the only factor of interest or concern; an iPad has only a finite space available to it, and filling that up with image data that most users are not going to need or want seems preferable to using more computational power for most cases.
One other thing to consider - on a gallery, you are strongly recommended to generate thumbnails which give you the best of both worlds: the smaller, more accessible image for general use and the full original image for 'best'.
If in doubt, benchmark with both and see how big the difference is in your application - and if the difference is something you can live with versus the space saving, go with JPEG.