这是关于图像和它们的大小为移动设备的问题。

This is a question regarding images and their sizes for mobile devices.

所以，假设我要为全手机屏幕图像。我假设的屏幕是320 * 480这里，这似乎是一致的。

So assume I want an image for the full mobile screen. I am assuming that the screen is 320*480 here, which seems consistent.

当我把在Photoshop或MS油漆或任何图像，我可以选择像素/英寸（好吧，也许不是油漆，但你明白我的意思）。 默认为72像素/英寸，这是要始终保持？的

When I make the image in Photoshop or MS Paint or whatever, I can choose the pixels/inch (ok, maybe not in paint, but you get my drift). The default is 72 pixels/inch, is this to be maintained at all times?

某些设备具有更高的dpi的 - 我认为默认为160 dpi的 - 这样的装置，该装置，比如说，240dpi，显示我相同的图像做我：

Some devices have a higher dpi - I think the "default" is 160 dpi - so for a device which is, say, 240dpi, to show my same image do I:

比例从320 * 480到480 * 640（即大小= oldSize *一百六十分之二百四十）图像上移 或 转到我的形象，改变像素/英寸到72 *一百六十○分之二百四？ Scale the image up from 320*480 to 480 * 640 (ie size = oldSize*240/160) Or Go to my image and change the pixel/inch to 72 * 240/160?

由于Android有大小，像这样：

Given that Android has sizes like so:

xlarge screens are at least 960dp x 720dp
large screens are at least 640dp x 480dp
normal screens are at least 470dp x 320dp
small screens are at least 426dp x 320dp

（从这个 http://developer.android.com/guide/practices/screens_support html的）

我是否可以认为通过扩大我的图片上/下和他们洗牌到正确的位置，我可以得到跨设备的兼容性。

I take it that by scaling my images up/down and shuffling them to the right location I can get cross-device compatability.

其次，而不是增加的图像大小，是它更好地只是做一个真正的大图像，并根据需要收缩呢？

Next, instead of increasing image sizes, is it better to just make a really big image and shrink it as needed?

有关iPad和iPhone，这是完全相同的问题，只是不同的数字！ 该手机是小320x480和视网膜是640×960，在iPad为1024x768和视网膜是，再次，大四倍。

For iPads and iPhones, it is the exact same question, just different numbers! The phones are 320x480 and Retina is 640x960, the iPad is 1024x768 and Retina is, again, four times as large.

所以，做图像放大或像素/英寸在Photoshop规模达？

So do the images scale up or the pixels/inch in Photoshop scale up?

我想到底我问： 什么是推荐的像素/英寸Photoshop进行图像？ 请问这个数字的变化，或图像尺寸变化？ 假设图像的机器人，应该在H图像尺寸，M，L文件夹中是最低的价值在Android规格，或者只是在最大？

I guess in the end I am asking: What is the recommended pixels/inch in Photoshop for an image? Does this number change, or the image size change? Assuming images for an Android, should the image size in the h,m,l folders be the minimum of the value in the Android specs, or just under the maximum?

推荐答案

该位要求类似于preparing图形打印与网络。如果您有印刷生产的经验，你就会知道，当放大并打印了72 PPI图象会显得非常像素化和模糊。相反，你需要重做的图像作为载体图像或使用高分辨率的照片，然后设置文件的分辨率约为300 PPI，以打印它不会造成图像质量损失。对于Android屏幕密度的工作原理类似，不同之处在于我们并没有改变文件的分辨率，只有图像的大小（即标准的 72 PPI 是罚款）。

The bitmap requirement is similar to preparing graphics for print vs. the Web. If you have any experience with print production, you’ll know that a 72 PPI image will look very pixelated and blurry when scaled up and printed. Instead, you would need to redo the image as a vector image or use a high-resolution photo and then set the file’s resolution at around 300 PPI in order to print it without any loss of image quality. Screen density for Android works similar, except that we’re not changing the file’s resolution, only the image’s size (i.e. standard 72 PPI is fine).

不要增加在Photoshop或Gimp任何决议改变你的形象只保留72ppi。

Don't increase any resolution in photoshop or gimp for changing your image keep 72ppi only.

刚刚比例从基线即MDPI图像= 1。

just scale the image from baseline i.e mdpi=1.

75 × 75 for low-density screens (i.e. ×0.75); 
100 × 100 for medium-density screens (our baseline);
133 x 133 fpr TVDPI (1.33)(no need to supply graphics android will auto scale from hdpi) 213/160=1.33125
150 × 150 for high-density screens (×1.5);
200 × 200 for extra high-density screens (×2.0).