Webp very low quality when converting transparent PNG image files - optimization

I want to use Webp and get my images much small, at last for serving them to chrome browsers. I've download many types of conversion tools, including the official one. I tried to convert PNG with Alpha transparency and get awful results. See image below..
According to what I see on many websites, it shold handle transparency incredibly well. I wanted to know if you know why I get these kind of results and what I need to do or what tool I need to produce high quality webp transparent images that will replace my png ones.
Second, I wanted to know the comparability. Should I server those images only for chrome uses? - OF course the most important issue is the image quality outpu.
Thanks

You are probably using an older version of WebP library/binary, which didn't have alpha support. So the images you see have alpha channel stripped.
Try again with the latest release v0.2.0:
http://code.google.com/p/webp/downloads/list

Related

JPEG RAW images not displaying in Safari on MacOS Sierra or iOS 10

We've recently had some users of our app report that JPEG images aren't displaying properly since they updated to iOS 10.
We've looked into it and found that some JPEG images do work OK, and some don't. There are no errors logged anywhere.
The ones that don't work in our app also don't work in Safari on iOS 10. Not only that, but they also don't work in Safari on MacOS Sierra.
So we've checked the files themselves out and found that the files that don't work begin ÿØÿÛ, while the others that do work OK begin ÿØÿá.
Googling these signatures led us to this page: https://en.wikipedia.org/wiki/List_of_file_signatures
Here it states that the images that aren't working are JPEG Raw, as opposed to JFIF or Exif format JPEGs.
So the question is: Why does this no longer work, and what's the best solution to work around it? I don't want to have to re-encode the images because of the lossy nature of JPEGs. We also can't get the source of these images to change, unfortunately.
We've considered a solution for our app, but that won't solve the problem in Safari.
There's always the wonder of why have Apple removed support for this format?

Tesseract cannot recognize my image correctly

I am developing an Android app now, it needs to recognize captcha from website.
I utilize the tess-two to recognize captcha and follow TrainingTesseract3 instructions to train my own traineddata (using jTessBoxEditor to correct characters), but it cannot recognize correctly and even cannot recognize it.
The below TIFF image is that I use to train my Tesseract, I collect many captchas and merge them into a image.
TIFF image
The image that I want to recognize
For example, the expected result of the above image should be k8666, but the actual result is only 66.
Does anyone give me a help? Thanks.
I tried your images using a .NET wrapper for tesseract-ocr Tesseract-ocr .Net Wrapper by Charliesw.
I got some better results like (K8EEE, K8656), i think you have to increase the text font and make it bold and i saved the image in tiff format with 96DPI resolution to get a better results than mine.

Using ImageOptim for *lossless* PNG optimization results in different color images

Google's PageSpeed tool told me to optimize my PNG images, which were saved for web in Photoshop. After researching lossless PNG compression options I downloaded ImageOptim and put a few images through it. The results have vastly different colors than the originals, which seems to indicate that this compression is actually lossy. Any suggestions?
Original image:
After ImageOptim:
Your image has embedded color profile, which for web is very wasteful and a compatibility headache.
For the web always export images in sRGB color, with no embedded profile, gamma 2.2.
http://imageoptim.com/color-profiles.html

ImageResizer minwidth / minheight for ebay images

Ebay now requires images to be 500x500.
I want to try to use ImageResizer to resize an image to be a minimum of 500x500 by adding white background padding
The following command achieves this quite easily.
product.jpg?width=500&height=500&scale=canvas
This works great, except when the original image is 800x800 and it will be downsized and lose quality.
What I really want to do is combine scale=canvas with scale=upscaleonly but that doesn't seem to be possible? Am I missing something or will I have to write code myself using the API.
PS. I realize ebay may detect whitespace and still reject the image, but I'm trying that for now - I have a lot of perfectly good 450x450 images that fall short and I don't want to upscale them.
At present, there's no 'upscalecanvasonly' mode.
So far we haven't had anyone else request this, but feel free to add it to our UserVoice site as a feature idea.
You could also implement this with a small IPlugin that subclassed BuilderExtension and implemented LayoutImage to support an additional command. It shouldn't be very difficult.
I haven't used ImageResizer before, but I've worked with images, so I took a quick peek at the basic commands for ImageResizer.
If I understand your problem correctly, when you downsize a 800x800 image it looses quality. This does point to a severe problem because the original image has more data than what is needed to display a high quality 500x500 image. Because of this, we must look at the image file format type and the data compression quality/method.
In your example, you are using the JPEG file format. You may want to specify the format in the command, i.e., format=jpg
In using the JPEG format, Imageresizer gives you control over the quality of the compression:
The documentation states:
quality - Jpeg compression: 0-100 100=best, 90=very good balance, 0=ugly
Take a look at the documentation for the exact verbage for setting the quality.

White image while inserting a SVG image in TCPDF

I'm trying to insert some SVG images in a PDF using TCPDF with the method TCPDF::ImageSVG, but when I try this I get a white space.
If I try to enable TCPDF::setRasterizeVectorImages the image shows in the PDF file, but it is rasterized of course and so its quality is not good.
Do you have any idea?
Thank you very much for your help!
Unfortunately, TCPDF's SVG handling is quite limited, and the cause of your issue depends on the SVG you are trying to use. Later versions of TCPDF support more SVG functionality, so if you haven't done so, try using a later version of TCPDF.
If an update doesn't resolve the issue, and you're forced to use raster images, you can improve quality at the cost of file size. You can do this by rasterizing them at a high DPI yourself outside of TCPDF. Once you've done this, take your new high-resolution raster image and add it to your PDF with the Image method like any other raster image. At work we usually rasterize to 300dpi, but your application may call for more or less.
If your image gets added to the PDF far larger on the page than you expected, specify at least one of the dimensions so TCPDF knows how much of the page you're intending the image to use.