blocks|key|1090622|text|您可以使用libpng将PNG图像转换为三字节(8:8:8)+RGB。然后，您可以对RGB565的5:6:5+16位颜色值进行下采样。如果r、g和b是各自的8位颜色(以无符号字符类型存储)，则16位RGB565值为：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1090623|((r+>>+3)+<<+11)+%7C+((g+>>+2)+<<+5)+%7C+(b+>>+3)|code-block|syntax|javascript|1090624|您可以通过舍入而不是斩波来改进这一点，注意不要使值溢出。当蓝色和红色值在原始8位值中都相等时，您还可以强制绿色值等于蓝色和红色值。否则，可能会使原本为灰色的颜色在转换后无意中呈现出颜色。|1090625|entityMap|0|LINK|mutability|MUTABLE|url|http://www.libpng.org/pub/png/libpng.html^0|1X|1|1Z|1|21|1|5|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|15|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

You can use <a href="http://www.libpng.org/pub/png/libpng.html" rel="noreferrer">libpng</a> to convert the PNG image to three-byte (8:8:8) RGB. Then you can downsample to the 5:6:5 16-bit color values of RGB565. If <code>r</code>, <code>g</code>, and <code>b</code> are the respective 8-bit colors (stored in an unsigned char type), then the 16-bit RGB565 value is:

<pre><code>((r &gt;&gt; 3) &lt;&lt; 11) | ((g &gt;&gt; 2) &lt;&lt; 5) | (b &gt;&gt; 3)
</code></pre>

You can improve a tad on this by rounding instead of chopping, being careful to not overflow the values. You can also force the green value to be equal to the blue and red values when they are all equal in the original 8-bit values. Otherwise it is possible to have colors that were originally gray inadvertently take on color after conversion.

blocks|key|1090250|text|根据维基百科(+Wikipedia+)的说法，唯一的16位PNG是灰度PNG。http://en.wikipedia.org/wiki/Portable_Network_Graphics|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1090251|如果您只是像往常一样将32位(alpha)或24位(无alpha)+PNG添加到您的项目中，然后在Cocos2D中设置纹理格式，那么一切都应该很好。它的代码是：|1090252|[CCTexture2D+setDefaultAlphaPixelFormat:kCCTexture2DPixelFormat_RGB565];|code-block|syntax|javascript|1090253|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Portable_Network_Graphics^0|13|1I|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

According to Wikipedia, which is always right, the only 16-bit PNG is a greyscale PNG. <a href="http://en.wikipedia.org/wiki/Portable_Network_Graphics" rel="nofollow">http://en.wikipedia.org/wiki/Portable_Network_Graphics</a>

If you just add your 32-bit (alpha) or 24-bit (no alpha) PNG to your project as normal, and then set the texture format in Cocos2D, all should be fine. The code for that is:

<pre><code>[CCTexture2D setDefaultAlphaPixelFormat:kCCTexture2DPixelFormat_RGB565];
</code></pre>

blocks|key|1716458|text|使用石英创建具有颜色RGB565的位图上下文，在此上下文上绘制您的PNG，将此位图上下文保存到文件中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1716459|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Create Bitmap Context with color RGB565 using Quartz, paint your PNG on this context, save this bitmap context to file.

blocks|key|73017|text|PNG不支持RGB565打包。您可以始终对图像应用色调(以编程方式或使用ImageMagick或任何图像编辑器)，这相当于丢弃每个通道中的较低有效位。保存为PNG格式时，每个通道仍可节省8位(除非您使用调色板)，但即使这样，由于PNG压缩，大小也会显著减小。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|73018|一个简单的例子:原创：|73019|​|73020|📷|atomic|offset|length|73021|73022|在使用XnView应用32个级别(相当于RGB555)的简单色散之后|73023|73024|73025|73026|大小从89KB增加到47KB，但质量损失很小。在具有梯度的合成图像的情况下，质量损失可能更明显(带状)。|73027|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b32996982b32c39e4f9ad57c2bd14991.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/a59a959a984e3ed6c2efcbf9885e5624.png^0|0|0|0|0|1|0|0|0|0|0|0|1|1|0|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|15|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|16|8|@]|9|@$I|17|J|18|1|19]]|A|$]]|$1|K|3|E|5|6|7|1A|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1B|8|@]|9|@]|A|$]]|$1|N|3|E|5|6|7|1C|8|@]|9|@]|A|$]]|$1|O|3|G|5|H|7|1D|8|@]|9|@$I|1E|J|1F|1|1G]]|A|$]]|$1|P|3|E|5|6|7|1H|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1I|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z|10|-4]]|11|$5|V|W|X|A|$Y|12|10|-4]]]]

PNG does not support a RGB565 packing. You can always apply a posterize to the image (programatically or with ImageMagick or with any image editor), which amounts to discard the lower significant bits in each channel. When saving to PNG, you will still be saving 8 bits per channel (unless you use a palette), but even then you will get an appreciable reduction in size, because of the PNG compression.

A quick example: original:

<img src="https://i.stack.imgur.com/hp0iH.png" alt="enter image description here">

after a simple posterize with 32 levels (equivalent to a RGB555) applied with XnView

<img src="https://i.stack.imgur.com/SNDOp.png" alt="enter image description here">

The size goes from 89KB to 47KB, with a small quality loss.
In case of synthetic images with gradients, the quality loss could be much more noticiable (banding).

blocks|key|1716599|text|我从texture+packer的创建者那里得到了这样的回答：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1716600|you+can+do+it+from+command+line+-+see|code-block|syntax|javascript|1716601|http://www.texturepacker.com/uncategorized/batch-converting-images-to-pvr-or-pvr-ccz/|offset|length|1716602|Just+adjust+the+opt+and+set+output+to+.png+instead+of+pvr.ccz
Make+sure+that+you+do+not+overwrite+your+source+images.|1716603|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|2D|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|U|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|V|8|@]|9|@$I|W|J|X|1|Y]]|A|$]]|$1|K|3|L|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|H]]]]

I received this answer from the creator of texture packer:

<pre><code>you can do it from command line - see
</code></pre>

<a href="http://www.texturepacker.com/uncategorized/batch-converting-images-to-pvr-or-pvr-ccz/" rel="nofollow">http://www.texturepacker.com/uncategorized/batch-converting-images-to-pvr-or-pvr-ccz/</a>

<pre><code>Just adjust the opt and set output to .png instead of pvr.ccz
Make sure that you do not overwrite your source images.
</code></pre>

How can I accomplish this? A programmatic solution (Objective-c) is great, but even a non-progarmmatic one is good.

I have pixelmator -> But that doesn't give you the option. I can't seem to do it with Preview either. 

I have tried googling, but haven't been able to find a solution so far. The only tool I have been able to use to do this is TexturePacker, but that creates a sprite sheet.

How to convert 32 bit PNG to RGB565?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我如何才能做到这一点呢？程序性解决方案(Objective-c)很好，但即使是非程序性解决方案也很好。我有pixelmator ->，但这不能给你选择。我似乎也不能用Preview做到这一点。我试过用谷歌搜索，但到目前为止还没有找到解决方案。我唯一能用来做这件事的工具是TexturePacker，但它创建了一个精灵工作...

问如何将32位PNG转换为RGB565？
EN

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问如何将32位PNG转换为RGB565？EN