png-24 | 易学教程

Transparent background png image issue in IE6

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问题 background image of type PNG is not transparent in ie6 回答1: See these posts IE6 PNG transparency How to use semi-transparent png images in IE6 回答2: This is a known issue in IE6: Transparent PNGs are only supported with some hacks. 回答3: This is a well-know bug. There are several workarounds, e.g. you can try using Google's ie7-js library. 回答4: I think you should definitely check the JQuery plugin called Supersleight, created by the guys on All In The Head & 24 Ways. They fixed some problems

Transparent background png image issue in IE6

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PHP Watermarking - Zubrag

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问题 I'm using zubrags PHP watermarking script (attached below) and it works great except when I try and use a PNG-24 as my watermark. The resulting image has a garbled, non-transparent watermark. I'm wondering if anyone could help explain what I would need to alter in the script below so that a PNG-24 embeds as a proper watermark on the image? I did come across this article: http://www.benholmen.com/blog/2008/12/adding-png-watermarks-to-jpegs-with-php/ which mentioned the use of PHP's

How can I tint transparent PNG files in PHP?

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问题 I have a transparent PNG image. The transparent areas need to remain completely transparent, but the other areas need tinting with a particular hue. What's the best way to do this using GD? Cheers, James 回答1: The above solution didn't work for me. You are filling alpha region here with red; that I believe is not the objective. Objective is to tint the rest of the image and leave the alpha unchanged. (Also, wrong use of function imagecolorallocate, you should use imagecolorallocatealpha.) I

Just in theory: How is the alpha component premultiplied into the other components of an PNG in iPhone OS, and how can it be unpremultiplied properly?

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问题 Actually, I thought that there would be an easy way to achieve that. What I need is pure alpha value information. For testing, I have a 50 x 55 px PNG, where on every edge a 5x5 pixel rectangle is fully transparent. In these areas alpha has to be 0.Everywhere else it has to be 255. I made very sure that my PNG is created correctly, and it also looks correctly. Please tell me if this is theoretically correct: I created an CGImageRef that has only the alpha channel and nothing else. This is

Convert 32bit PNG file to 24bit PNG file

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问题 How to convert 32bit PNG file to 24bit PNG file using PHP. btw I am using Codeigniter, and planning to host files at Dreamhost. Thanks! 回答1: Give this a try: exec('convert -depth 24 /path/to/old/image.png /path/to/new/image.png'); There is a PEAR package for ImageMagick, although making a system call also works if your hosting provider hasn't installed the PEAR package. 来源： https://stackoverflow.com/questions/7658679/convert-32bit-png-file-to-24bit-png-file

Convert 32bit PNG file to 24bit PNG file

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How to convert 32bit PNG file to 24bit PNG file using PHP. btw I am using Codeigniter, and planning to host files at Dreamhost. Thanks! Give this a try: exec('convert -depth 24 /path/to/old/image.png /path/to/new/image.png'); There is a PEAR package for ImageMagick, although making a system call also works if your hosting provider hasn't installed the PEAR package. 来源： https://stackoverflow.com/questions/7658679/convert-32bit-png-file-to-24bit-png-file

What is difference between png8 and png24

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问题 I want to know about uses of png files. There are two formats available for png images ; one is png8 and the another one is png24 . I would like to know that if I use either type in my html page, will there be any error? Or is this only quality matter? 回答1: There is only one PNG format, but it supports 5 color types. PNG-8 refers to palette variant, which supports only 256 colors, but is usually smaller in size. PNG-8 can be a GIF substitute. PNG-24 refers to true color variant, which

Just in theory: How is the alpha component premultiplied into the other components of an PNG in iPhone OS, and how can it be unpremultiplied properly?

阅读更多关于 Just in theory: How is the alpha component premultiplied into the other components of an PNG in iPhone OS, and how can it be unpremultiplied properly?

Actually, I thought that there would be an easy way to achieve that. What I need is pure alpha value information. For testing, I have a 50 x 55 px PNG, where on every edge a 5x5 pixel rectangle is fully transparent. In these areas alpha has to be 0.Everywhere else it has to be 255. I made very sure that my PNG is created correctly, and it also looks correctly. Please tell me if this is theoretically correct: I created an CGImageRef that has only the alpha channel and nothing else. This is done with CGBitmapContextCreate and kCGImageAlphaOnly as param. CGBitmapContextGetBitsPerPixel(context)

What is difference between png8 and png24

阅读更多关于 What is difference between png8 and png24

I want to know about uses of png files. There are two formats available for png images ; one is png8 and the another one is png24 . I would like to know that if I use either type in my html page, will there be any error? Or is this only quality matter? There is only one PNG format, but it supports 5 color types . PNG-8 refers to palette variant, which supports only 256 colors, but is usually smaller in size. PNG-8 can be a GIF substitute. PNG-24 refers to true color variant, which supports more colors, but might be bigger. PNG-24 can be used instead of JPEG, if lossless image format is needed.