使用 GDIPlus 调整大小模糊顶部边缘
我正在使用以下代码来使用 C 中的 GDI+ 调整位图大小。即使对于该区域应该为白色的图像，我也获得了顶部边缘的灰度值。当插值是最近邻时，问题就消失了。但是，我尝试使用 ImageMagick 进行双三次插值，看起来不错。我应该知道什么限制问题吗？我的缩放方法是否错误？谢谢！
（输入： destSize : 目标 Gdiplus::Size m_pBitmap ：源位图）
Rect destRect(Point(0,0), destSize);
Bitmap *pBitmap24BPP = new Bitmap(destSize.Width, destSize.Height, PixelFormat24bppRGB);
pBitmap24BPP->SetResolution(m_pBitmap->GetHorizontalResolution(), m_pBitmap->GetVerticalResolution());
Graphics *pGraphics = Graphics::FromImage(pBitmap24BPP);
pGraphics->SetInterpolationMode(InterpolationModeHighQualityBilinear);
pGraphics->DrawImage(m_pBitmap, destRect, 0, 0, m_pBitmap->GetWidth(), m_pBitmap->GetHeight() , UnitPixel, NULL);
//cleanup
I'm using the following code to resize a bitmap using GDI+ in C. I'm getting gray values for the top edge even for images where that area should be white. The problem disappears when the interpolation is nearest neighbor. However, I tried bicubic interpolation with ImageMagick and it seems fine. Any limitations problems I should know of? Is my method of scaling wrong somehow? Thanks!
(inputs:
destSize : destination Gdiplus::Size
m_pBitmap : source bitmap)
Rect destRect(Point(0,0), destSize);
Bitmap *pBitmap24BPP = new Bitmap(destSize.Width, destSize.Height, PixelFormat24bppRGB);
pBitmap24BPP->SetResolution(m_pBitmap->GetHorizontalResolution(), m_pBitmap->GetVerticalResolution());
Graphics *pGraphics = Graphics::FromImage(pBitmap24BPP);
pGraphics->SetInterpolationMode(InterpolationModeHighQualityBilinear);
pGraphics->DrawImage(m_pBitmap, destRect, 0, 0, m_pBitmap->GetWidth(), m_pBitmap->GetHeight() , UnitPixel, NULL);
//cleanup
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我也见过类似的事情。我没有时间研究它，但我有一种感觉，这是因为 GDI+ 图像缩放器错误地使用了“离开顶部边缘”的像素值，这将全部为零 - 使其变黑。
正确的图像调整大小应该识别出您已经到达图像的边缘，并进行适当的处理。
i've been seeing similar things. i've not had time to research it, but i have a feeling it is because the GDI+ image resizer is mistakenly using pixels values "off the top edge", which would be all zero - making it black.
Proper image resizing should recognize that you've reached the edge of the image, and handle it appropriately.