gimp 尺寸调整

Brightness and Contrast tools are for beginners! Ever wondered what graphics programs offer advanced users to ensure their photographs have a great value range? Read on to learn about Levels, Curves, and Histograms in three major programs.

亮度和对比度工具适合初学者！ 有没有想过哪种图形程序可以为高级用户提供确保其照片具有巨大价值的选择？ 继续阅读以了解三个主要程序中的水平，曲线和直方图。

Curves and Levels are not as intuitive as the more basic Brightness and Contrast sliders Photoshop, GIMP, and Paint.NET all share. However, they offer a great deal more control over images that professionals and skilled image editors will demand. Combine these tools with a knowledge of how basic histograms work, and you’ll be well on your way to editing contrast like a pro!

曲线和色阶不像Photoshop，GIMP和Paint.NET共享的更基本的“亮度和对比度”滑块那样直观。 但是，它们提供了对专业人员和熟练的图像编辑人员所需的图像的更多控制。 将这些工具与基本直方图的工作原理结合起来，您将可以像专业人士一样轻松编辑对比度！

什么是直方图？ (What is a Histogram?)

Histograms are confusing looking collections of information, and are not obviously understood unless they are explained. The left is the histogram tool in Photoshop (Window > Histogram), the right is the Histogram tool in the GIMP (Colors > Info >Histogram). Out of the box, Paint.NET does not have a stand alone Histogram tool, but has them built into other tools that we will discuss later.

直方图会使信息看起来很混乱，除非对其进行解释，否则显然不会被理解。 左侧是Photoshop中的直方图工具(“窗口”>“直方图”)，右侧是GIMP中的直方图工具(“颜色”>“信息”>“直方图”)。 开箱即用，Paint.NET没有独立的直方图工具，但已将其内置到其他工具中，我们将在后面讨论。

You can think of a histogram as a sort of simple algebraic mapping of the information in your image. Your horizontal (x axis) represents your value range, from your darkest blacks on your left side, to your lightest whites on your right. Your vertical (y axis) shows the concentration of that value in your image. The higher the peaks, the more of that color is in your image. High peaks on the right side represents high amounts of light values, highlights and whites, while high peaks on the left represents a high concentration of dark, black, low light values.

您可以将直方图视为图像中信息的一种简单的代数映射。 水平(x轴)代表您的值范围，从左侧的最暗黑色到右侧的最亮白色。 您的垂直(y轴)显示了该值在图像中的浓度。 峰越高，图像中的颜色越多。 右侧的高峰代表大量的光值，高光和白色，而左侧的高峰代表高浓度的暗，黑，低光值。

Histograms can be made for any color channel, or for combinations of those channels, although you might see quite different information depending on which you are looking at. Remember that all photographs are made of image channels, all of which have their own range of values, but can also be combined to create a complete image. Regardless of all that, you can learn a lot of useful information checking out how the values are distributed in your images.

直方图可以用于任何颜色通道，也可以用于这些通道的组合，尽管根据所查看的内容您可能会看到完全不同的信息。 请记住，所有照片都是由图像通道组成的，所有通道都有自己的取值范围，但也可以组合以创建完整的图像。 无论如何，您都可以学到很多有用的信息，以检查值在图像中的分布方式。

亮度和对比度工具 (Brightness and Contrast Tools)

Brightness and contrast, as we discussed, are easy to understand methods for editing photographs. They give you only basic edits to your value range, clunkily bloating, stretching, and distorting your value range, giving less than perfect control over the parts of your histogram you want to change. Pictured above are the Brightness and Contrast tools for Paint.NET (left) and the GIMP (right).

正如我们所讨论的，亮度和对比度是易于理解的照片编辑方法。 它们仅给您对值范围的基本编辑，笨拙地膨胀，拉伸和扭曲值范围，从而对要更改的直方图的各个部分的控制不够完美。 上图是Paint.NET(左)和GIMP(右)的亮度和对比度工具。

Ideally, a good, balanced image should have good detail in the lights and darks, as well as a good value range throughout, without a lot of dynamic high peaks in any area. Brightness and contrast tools simply “stretch” the entire range out to create brighter images, leaving gaps in the histogram without bringing out details in either the highlights or darks.

理想情况下，一个好的，平衡的图像应该在明暗之间具有良好的细节，并且在整个范围内都具有良好的值范围，并且在任何区域都不应有很多动态的高峰值。 亮度和对比度工具只是简单地“拉伸”整个范围以创建更明亮的图像，从而在直方图中留有空隙，而不会在高光或暗处显示细节。

使用关卡 (Working with Levels)

Levels are the superior tool for adjusting histograms, and bringing out rich value ranges in an image. GIMP’s Levels tool (left) and Photoshop’s (right) look very similar. They have two basic sliders, one for Input Levels, and another for Output Levels.

级别是用于调整直方图并带出图像中丰富的值范围的高级工具。 GIMP的色阶工具(左)和Photoshop的(右)看起来非常相似。 它们有两个基本的滑块，一个用于输入级别 ，另一个用于输出级别 。

Input levels allow you to adjust your range of values by adjusting three points within the horizontal axis. Moving the “Darks” point will make all of your darks heavier and blacker. Adjusting your “Lights” point will make all of your highlights brighter and lighter. And adjusting the middle point will cause your value range to lean one way or another, either lighter or darker, effectively compressing that part of the old histogram, while stretching out detail in other parts.

输入电平允许您通过调整水平轴上的三个点来调整值的范围。 移动“暗”点将使您所有的暗都更重，更黑。 调整“灯光”点将使您所有的高光越来越亮。 调整中间点将使您的值范围变淡或变深，从而有效压缩旧直方图的该部分，同时扩展其他部分的细节。

Output Levels give you direct control of the Y-Axis of your histogram, and allow you to set a ceiling for how dark your darks can be, and how light your lights can be. Used in combination with adjustments to Input Levels, detail can be coaxed out of even stubborn images.

输出电平使您可以直接控制直方图的Y轴，并可以为黑暗设置为多深以及灯光设置为多高设置一个上限。 与输入电平的调整结合使用，即使是顽固的图像也可以使细节消失。

It is worth noting that Paint.NET’s Levels tool is slightly different than either Photoshop or GIMP. It is no more complicated than either, and a basic understanding of histograms and some patience will allow you to make any adjustment you could make in Photoshop or GIMP.

值得注意的是，Paint.NET的色阶工具与Photoshop或GIMP略有不同。 两者都不复杂，对直方图的基本了解和一些耐心将使您能够进行可以在Photoshop或GIMP中进行的任何调整。

如何使用曲线 (How to Use Curves)

Curves are yet another way to look at adjusting the same color information, with the exception that it is a considerably more complex tool, allowing for fine tuning and microadjustments to images.

曲线是查看相同颜色信息的另一种方法，不同之处在于它是一种相当复杂的工具，可以对图像进行微调和微调整。

On the basic curve, the vertical axis represents the Output Levels, which sort of turns your histogram on its head. In its natural state, the “curves” line represents a 1:1 ratio, or a straight rise/run diagonal line. This means that the darkest parts of the horizontally noted values should have an equal, corresponding value in your vertical axis. What does all this mean? Basically, you have the ability to subtly put a ceiling on your lights and darks, while creating potentially complex adjustments to the other parts of your image.

在基本曲线上，垂直轴表示“输出电平”，它可以改变直方图的头部。 在其自然状态下，“曲线”线代表1：1的比率，或者是直线上升/延伸的对角线。 这意味着水平标注值中最暗的部分在垂直轴上应具有相等的对应值。 这是什么意思呢？ 基本上，您可以巧妙地在明暗处设置天花板，同时对图像的其他部分进行可能复杂的调整。

Drastically different images can be created by distorting curves. Midtones can be made into highlights, darks into lights, highlights into midtones, and all with the same basic set of tools.

通过扭曲曲线可以创建截然不同的图像。 可以使用相同的基本工具将中间调变成高光，将暗变成光，将高光变成中音。

For even further complication, curves can be adjusted per channel, like Levels. This allows for an impressive level of customization, allowing graphics power users to coax better, richer information by editing channels independently and together. This can allow you to, perhaps, shift your highlights to be more yellow or gray, while making your shadows more red or blue. Curves can prove a vital set of tools for any photographer, from amateur to seasoned pro.

为了进一步提高复杂度，可以像“色阶”一样按通道调整曲线。 这样可以实现令人印象深刻的自定义级别，使图形能力强大的用户可以通过独立并一起编辑通道来更好地获取更丰富的信息。 这可能使您可以将高光更改为更多的黄色或灰色，同时使阴影更更改为红色或蓝色。 从业余爱好者到经验丰富的专业人士，曲线对于任何摄影师而言都是一套至关重要的工具。

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While the program’s visuals may differ slightly from Photoshop to GIMP to Paint.NET, you can expect the power of these tools to remain the same. Expect some minor differences in the user interface, with the core functionality intact.

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尽管从Photoshop到GIMP到Paint.NET，该程序的视觉效果可能略有不同，但是您可以期望这些工具的功能保持不变。 在核心功能完好无损的情况下，用户界面可能会有一些细微的差别。

Image Credit: All images by Guillaume Boppe, available under Creative Commons.

图片来源： Guillaume Boppe的 所有图片 ，可在“ 创用CC”下找到 。

翻译自: https://www.howtogeek.com/howto/44826/learn-to-adjust-contrast-like-a-pro-in-photoshop-gimp-and-paint.net/

gimp 尺寸调整