I have unsuccessfully browsed this site (that has so often saved my life in the past) and the web for an answer to this question:
I use Java, XSL-FO and FOP to generate PDFs that consist in one or more pages of data and images, each page having a header and a footer containing images themselves. These header and footer are repeated on each and every page of the PDF documents.
The images are responsible for a large part of the size of the resulting PDF (about 50 %). I noticed that, by converting them from JPEG to TIFF, and by reducing their resolution, I was able to reduce considerably the size of the PDF as well. But I now have the feeling that I have reached a dead-end as far as images as concerned.
The PDFs are still very huge, compared to those that used to be generated with FrameMaker, the Adobe PDF generation system that we're willing to get rid of. And I'm sorry to say that I can't think of another way to reduce the PDFs' size, as the Web mainly talks about pre-processing images in order to make PDFs smaller.
I was wondering whether, maybe, it would be possible in a way or another to tell FOP to repeat the images in all headers and footers in some kind of way so that the images would be embedded only once in the document and just "mirrored" on the other pages.
Plus, there ought to be other ways to reduce the PDF size, apart from images, don't you think?
I would highly appreciate any advice on this topic. Thanks a lot in advance for your time and help.
Erwann
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I wanted to scan Book pages and combine the images to an pdf "ebook" (just for me), but the file sizes get really huge. Even .jpg resulted in an pdf file with 60mb+ in size.
Do you have any idea how I can compress it any further? I.e. which file format I could choose for this specific purpose? (The book contains pictures and written text.)
Thank you for your help.
I tried to save it as .jpg and other file formats like .png, but didnt get small enough for the file to be easy handled, without loosing to much resolution.
Images are expensive things.
Ignoring compression you’re looking at 3bytes per pixel of data.
If you want to keep images you could reduce this by turning your images into greyscale. That reduces it to 1byte per pixel (again ignoring compression).
Or you could turn it into black and white. Which would be 1 but per pixel.
Or, alternatively, you could use OCR to translate your image into actual text which is a much more efficient way of storing books.
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.
I asked this question recently: How can I create a CSS border on a diagonal element
Question: Is it more memory intensive or cpu intensive to use image or complex css for a navigation menu?
Question: Cross browser/screen size aside, is the an advantage to one over the other for reasons other than what is mentioned above?
Thank you!
Ultimately, the device needs to display an array of pixels. If you send an image file of those pixels, they are ready for display. If you send complex css for creating those pixels, it will likely take fewer bytes across the network but the processor will need to render the pixel array before it can be displayed.
Whether you should use css or an image depends on a variety of considerations. Here are a few:
Is the thing you need to display always exactly the same size? Then an image file has the advantage of already being rendered. If not, css will give the capability to size efficiently.
Will the user always have a good network connection? If so, there won't be as much of a performance penalty for sending a pre-rendered image and possibly a bunch of media query css to decide which image to load.
Is the thing you are trying to render very large on screen? If so, css might have an advantage over loading a large image file.
Is the css extremely complex, taking lots of code to describe? Then an image file has the cpu advantage of being pre-processed.
Are there animation states or other animation associated with the display item? Then css has the advantage of not having to load multiple potentially large image files. But, if the states have very complex animation taking lots of code and therefore cpu, then the previous guideline will apply.
Second question: If there are cross-browser difficulties with your css, a pre-rendered image will eliminate those. But, if you are building a responsive display object that has very many different display sizes, css will have the advantage of scalability. That said, a basic concept in responsive design would be to provide a few different size versions of an image.
In general, image files cost bandwidth and css/vectors cost cpu.
I'm trying to optimize a page which loads a lot of images from S3 and which needs to run on mobile devices, too.
Images are available in S,M,L,XL resolutions, so on a smartphone I'm usually pulling Size M for the grid thumbnail images. These pictures measure: 194x230px and usually "weigh" around 20k, which I think is far too much.
Question:
If I use Irfan and the RIOT plugin, I can easily shave off 10k from the filesize with the image still looking ok. I'm wondering if there are any guidelines regarding optimal image filesize in relation to image dimensions or is this purely a trial and error process? As a side question, is there any server-side tool, which also uses the RIOT plugin?
Thanks!
My program save images from a camera in a rate about 30fps;
Moving these images or browsing them by windows explorer take a long time.
My questions is:
is storing them as a video file is a better approach? so moving files wouldn't take a lot of time. (if this is good, how to open a large video file and get a specified frame number fast? Is this approach faster?)
It's very unlikely that a video file will load or seek any faster than individual image files. Not to mention this is going to be a lot more difficult to handle than images, and probably introduce a bunch of extra, unnecessary dependencies to your application.
If you really need a way to speed up image browsing, you should look into generating separate thumbnail images. Thumbnails are exact duplicates of the original images, but with significant reductions in size and quality, suitable for display purposes only. This makes the resulting thumbnail images significantly smaller than the originals, which should speed up their loading and rendering substantially. This trick is used all over graphics packages and file managers. This approach allows you to delay the expensive process of loading the associated full image until after the user selects a particular thumbnail image to open.