将 YUV_420_888 转换为 JPEG 并保存文件导致图像失真
Converting YUV_420_888 to JPEG and saving file results distorted image
我使用了 within my git repo: https://github.com/ahasbini/cameraview/tree/camera_preview_imp 中提供的 ImageUtil
class(注意实现在 camera_preview_imp
分支中)来实现帧预览回调。 ImageReader
设置为预览 ImageFormat.YUV_420_888
格式的帧,使用 ImageUtil
class 将其转换为 ImageFormat.JPEG
并将其发送到帧回调。演示应用程序每 50 帧将回调中的一帧保存到一个文件中。所有保存的帧图像都出现类似于以下的失真:
如果我通过在 Camera2
中进行以下更改,将 ImageReader
更改为使用 ImageFormat.JPEG
:
mPreviewImageReader = ImageReader.newInstance(previewSize.getWidth(),
previewSize.getHeight(), ImageFormat.JPEG, /* maxImages */ 2);
mCamera.createCaptureSession(Arrays.asList(surface, mPreviewImageReader.getSurface()),
mSessionCallback, null);
图像正常显示,没有任何失真,但帧速率显着下降并且视图开始滞后。因此我认为 ImageUtil
class 没有正确转换。
已更新 ImageUtil:
public final class ImageUtil {
public static byte[] NV21toJPEG(byte[] nv21, int width, int height, int quality) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
yuv.compressToJpeg(new Rect(0, 0, width, height), quality, out);
return out.toByteArray();
}
// nv12: true = NV12, false = NV21
public static byte[] YUV_420_888toNV(ByteBuffer yBuffer, ByteBuffer uBuffer, ByteBuffer vBuffer, boolean nv12) {
byte[] nv;
int ySize = yBuffer.remaining();
int uSize = uBuffer.remaining();
int vSize = vBuffer.remaining();
nv = new byte[ySize + uSize + vSize];
yBuffer.get(nv, 0, ySize);
if (nv12) {//U and V are swapped
vBuffer.get(nv, ySize, vSize);
uBuffer.get(nv, ySize + vSize, uSize);
} else {
uBuffer.get(nv, ySize , uSize);
vBuffer.get(nv, ySize + uSize, vSize);
}
return nv;
}
public static byte[] YUV_420_888toI420SemiPlanar(ByteBuffer yBuffer, ByteBuffer uBuffer, ByteBuffer vBuffer,
int width, int height, boolean deInterleaveUV) {
byte[] data = YUV_420_888toNV(yBuffer, uBuffer, vBuffer, deInterleaveUV);
int size = width * height;
if (deInterleaveUV) {
byte[] buffer = new byte[3 * width * height / 2];
// De-interleave U and V
for (int i = 0; i < size / 4; i += 1) {
buffer[i] = data[size + 2 * i + 1];
buffer[size / 4 + i] = data[size + 2 * i];
}
System.arraycopy(buffer, 0, data, size, size / 2);
} else {
for (int i = size; i < data.length; i += 2) {
byte b1 = data[i];
data[i] = data[i + 1];
data[i + 1] = b1;
}
}
return data;
}
}
以 JPEG 格式写入文件 byte[] data
的操作:
//image.getPlanes()[0].getBuffer(), image.getPlanes()[1].getBuffer()
//image.getPlanes()[2].getBuffer(), image.getWidth(), image.getHeight()
byte[] nv21 = ImageUtil.YUV_420_888toI420SemiPlanar(yBuffer, uBuffer, vBuffer, width, height, false);
byte[] data = ImageUtil.NV21toJPEG(nv21, width, height, 100);
//now write `data` to file
!!!处理后不要忘记关闭图像!!!
image.close();
@volodymyr-kulyk 提供的解决方案没有考虑图像中平面的行步幅。下面的代码可以解决问题(image
是 android.media.Image
类型):
data = NV21toJPEG(YUV420toNV21(image), image.getWidth(), image.getHeight(), 100);
以及实现:
private static byte[] NV21toJPEG(byte[] nv21, int width, int height, int quality) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
yuv.compressToJpeg(new Rect(0, 0, width, height), quality, out);
return out.toByteArray();
}
private static byte[] YUV420toNV21(Image image) {
Rect crop = image.getCropRect();
int format = image.getFormat();
int width = crop.width();
int height = crop.height();
Image.Plane[] planes = image.getPlanes();
byte[] data = new byte[width * height * ImageFormat.getBitsPerPixel(format) / 8];
byte[] rowData = new byte[planes[0].getRowStride()];
int channelOffset = 0;
int outputStride = 1;
for (int i = 0; i < planes.length; i++) {
switch (i) {
case 0:
channelOffset = 0;
outputStride = 1;
break;
case 1:
channelOffset = width * height + 1;
outputStride = 2;
break;
case 2:
channelOffset = width * height;
outputStride = 2;
break;
}
ByteBuffer buffer = planes[i].getBuffer();
int rowStride = planes[i].getRowStride();
int pixelStride = planes[i].getPixelStride();
int shift = (i == 0) ? 0 : 1;
int w = width >> shift;
int h = height >> shift;
buffer.position(rowStride * (crop.top >> shift) + pixelStride * (crop.left >> shift));
for (int row = 0; row < h; row++) {
int length;
if (pixelStride == 1 && outputStride == 1) {
length = w;
buffer.get(data, channelOffset, length);
channelOffset += length;
} else {
length = (w - 1) * pixelStride + 1;
buffer.get(rowData, 0, length);
for (int col = 0; col < w; col++) {
data[channelOffset] = rowData[col * pixelStride];
channelOffset += outputStride;
}
}
if (row < h - 1) {
buffer.position(buffer.position() + rowStride - length);
}
}
}
return data;
}
方法取自以下link.
Camera2 YUV_420_888 到 Java(Android) 中的 Jpeg:
@Override
public void onImageAvailable(ImageReader reader){
Image image = null;
try {
image = reader.acquireLatestImage();
if (image != null) {
byte[] nv21;
ByteBuffer yBuffer = mImage.getPlanes()[0].getBuffer();
ByteBuffer uBuffer = mImage.getPlanes()[1].getBuffer();
ByteBuffer vBuffer = mImage.getPlanes()[2].getBuffer();
int ySize = yBuffer.remaining();
int uSize = uBuffer.remaining();
int vSize = vBuffer.remaining();
nv21 = new byte[ySize + uSize + vSize];
//U and V are swapped
yBuffer.get(nv21, 0, ySize);
vBuffer.get(nv21, ySize, vSize);
uBuffer.get(nv21, ySize + vSize, uSize);
String savingFilepath = getYUV2jpg(nv21);
}
} catch (Exception e) {
Log.w(TAG, e.getMessage());
}finally{
image.close();// don't forget to close
}
}
public String getYUV2jpg(byte[] data) {
File imageFile = new File("your parent directory", "picture.jpeg");//no i18n
BufferedOutputStream bos = null;
try {
bos = new BufferedOutputStream(new FileOutputStream(imageFile));
bos.write(data);
bos.flush();
bos.close();
} catch (IOException e) {
return e.getMessage();
} finally {
try {
if (bos != null) {
bos.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
return imageFile.getAbsolutePath();
}
注意:处理图片旋转问题。
我认为这里对 YUV 的 NV 和 YV 格式有些混淆。 NV(半平面)有交错U/V。 YV(平面)没有。所以这里进行的转换是 YV12/21 而不是 NV12/21.
我使用了 ImageUtil
class(注意实现在 camera_preview_imp
分支中)来实现帧预览回调。 ImageReader
设置为预览 ImageFormat.YUV_420_888
格式的帧,使用 ImageUtil
class 将其转换为 ImageFormat.JPEG
并将其发送到帧回调。演示应用程序每 50 帧将回调中的一帧保存到一个文件中。所有保存的帧图像都出现类似于以下的失真:
如果我通过在 Camera2
中进行以下更改,将 ImageReader
更改为使用 ImageFormat.JPEG
:
mPreviewImageReader = ImageReader.newInstance(previewSize.getWidth(),
previewSize.getHeight(), ImageFormat.JPEG, /* maxImages */ 2);
mCamera.createCaptureSession(Arrays.asList(surface, mPreviewImageReader.getSurface()),
mSessionCallback, null);
图像正常显示,没有任何失真,但帧速率显着下降并且视图开始滞后。因此我认为 ImageUtil
class 没有正确转换。
已更新 ImageUtil:
public final class ImageUtil {
public static byte[] NV21toJPEG(byte[] nv21, int width, int height, int quality) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
yuv.compressToJpeg(new Rect(0, 0, width, height), quality, out);
return out.toByteArray();
}
// nv12: true = NV12, false = NV21
public static byte[] YUV_420_888toNV(ByteBuffer yBuffer, ByteBuffer uBuffer, ByteBuffer vBuffer, boolean nv12) {
byte[] nv;
int ySize = yBuffer.remaining();
int uSize = uBuffer.remaining();
int vSize = vBuffer.remaining();
nv = new byte[ySize + uSize + vSize];
yBuffer.get(nv, 0, ySize);
if (nv12) {//U and V are swapped
vBuffer.get(nv, ySize, vSize);
uBuffer.get(nv, ySize + vSize, uSize);
} else {
uBuffer.get(nv, ySize , uSize);
vBuffer.get(nv, ySize + uSize, vSize);
}
return nv;
}
public static byte[] YUV_420_888toI420SemiPlanar(ByteBuffer yBuffer, ByteBuffer uBuffer, ByteBuffer vBuffer,
int width, int height, boolean deInterleaveUV) {
byte[] data = YUV_420_888toNV(yBuffer, uBuffer, vBuffer, deInterleaveUV);
int size = width * height;
if (deInterleaveUV) {
byte[] buffer = new byte[3 * width * height / 2];
// De-interleave U and V
for (int i = 0; i < size / 4; i += 1) {
buffer[i] = data[size + 2 * i + 1];
buffer[size / 4 + i] = data[size + 2 * i];
}
System.arraycopy(buffer, 0, data, size, size / 2);
} else {
for (int i = size; i < data.length; i += 2) {
byte b1 = data[i];
data[i] = data[i + 1];
data[i + 1] = b1;
}
}
return data;
}
}
以 JPEG 格式写入文件 byte[] data
的操作:
//image.getPlanes()[0].getBuffer(), image.getPlanes()[1].getBuffer()
//image.getPlanes()[2].getBuffer(), image.getWidth(), image.getHeight()
byte[] nv21 = ImageUtil.YUV_420_888toI420SemiPlanar(yBuffer, uBuffer, vBuffer, width, height, false);
byte[] data = ImageUtil.NV21toJPEG(nv21, width, height, 100);
//now write `data` to file
!!!处理后不要忘记关闭图像!!!
image.close();
@volodymyr-kulyk 提供的解决方案没有考虑图像中平面的行步幅。下面的代码可以解决问题(image
是 android.media.Image
类型):
data = NV21toJPEG(YUV420toNV21(image), image.getWidth(), image.getHeight(), 100);
以及实现:
private static byte[] NV21toJPEG(byte[] nv21, int width, int height, int quality) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
yuv.compressToJpeg(new Rect(0, 0, width, height), quality, out);
return out.toByteArray();
}
private static byte[] YUV420toNV21(Image image) {
Rect crop = image.getCropRect();
int format = image.getFormat();
int width = crop.width();
int height = crop.height();
Image.Plane[] planes = image.getPlanes();
byte[] data = new byte[width * height * ImageFormat.getBitsPerPixel(format) / 8];
byte[] rowData = new byte[planes[0].getRowStride()];
int channelOffset = 0;
int outputStride = 1;
for (int i = 0; i < planes.length; i++) {
switch (i) {
case 0:
channelOffset = 0;
outputStride = 1;
break;
case 1:
channelOffset = width * height + 1;
outputStride = 2;
break;
case 2:
channelOffset = width * height;
outputStride = 2;
break;
}
ByteBuffer buffer = planes[i].getBuffer();
int rowStride = planes[i].getRowStride();
int pixelStride = planes[i].getPixelStride();
int shift = (i == 0) ? 0 : 1;
int w = width >> shift;
int h = height >> shift;
buffer.position(rowStride * (crop.top >> shift) + pixelStride * (crop.left >> shift));
for (int row = 0; row < h; row++) {
int length;
if (pixelStride == 1 && outputStride == 1) {
length = w;
buffer.get(data, channelOffset, length);
channelOffset += length;
} else {
length = (w - 1) * pixelStride + 1;
buffer.get(rowData, 0, length);
for (int col = 0; col < w; col++) {
data[channelOffset] = rowData[col * pixelStride];
channelOffset += outputStride;
}
}
if (row < h - 1) {
buffer.position(buffer.position() + rowStride - length);
}
}
}
return data;
}
方法取自以下link.
Camera2 YUV_420_888 到 Java(Android) 中的 Jpeg:
@Override
public void onImageAvailable(ImageReader reader){
Image image = null;
try {
image = reader.acquireLatestImage();
if (image != null) {
byte[] nv21;
ByteBuffer yBuffer = mImage.getPlanes()[0].getBuffer();
ByteBuffer uBuffer = mImage.getPlanes()[1].getBuffer();
ByteBuffer vBuffer = mImage.getPlanes()[2].getBuffer();
int ySize = yBuffer.remaining();
int uSize = uBuffer.remaining();
int vSize = vBuffer.remaining();
nv21 = new byte[ySize + uSize + vSize];
//U and V are swapped
yBuffer.get(nv21, 0, ySize);
vBuffer.get(nv21, ySize, vSize);
uBuffer.get(nv21, ySize + vSize, uSize);
String savingFilepath = getYUV2jpg(nv21);
}
} catch (Exception e) {
Log.w(TAG, e.getMessage());
}finally{
image.close();// don't forget to close
}
}
public String getYUV2jpg(byte[] data) {
File imageFile = new File("your parent directory", "picture.jpeg");//no i18n
BufferedOutputStream bos = null;
try {
bos = new BufferedOutputStream(new FileOutputStream(imageFile));
bos.write(data);
bos.flush();
bos.close();
} catch (IOException e) {
return e.getMessage();
} finally {
try {
if (bos != null) {
bos.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
return imageFile.getAbsolutePath();
}
注意:处理图片旋转问题。
我认为这里对 YUV 的 NV 和 YV 格式有些混淆。 NV(半平面)有交错U/V。 YV(平面)没有。所以这里进行的转换是 YV12/21 而不是 NV12/21.