请大家帮忙分析一下这张图的缺陷是怎么引起的

runlywell

物体的边缘本来应当是直线，而图中边缘出现了锯齿，不知道是什么原因，请大家帮忙分析一下，谢谢！
[upload=jpg]UploadFile/2007-6/07620@52RD_sercomm-jaggies.JPG[/upload]

wong

放大看就正常了吧？

yanyanwu

可能是你软件设置方面的问题

chiefhe

YUV或RGB的配对错误. 应该有解.
搂主用哪家sensor?什么型号?YUV还是RGB数据格式?
[br]<p align=right><font color=red>+1 RD币</font></p>

ming688

可以在软件方面改善,不能完全解决.

pantuzi

很显然是isp 的edge值太大了，减小就OK了[em02]

chiefhe

锯齿不能简单定位为edge太强.
数据配对错误一定会有锯齿.

jjyy

step size in quatization table too big

jjyy

if YUV components not matches each other, you should see wrong color not 锯齿[br]<p align=right><font color=red>+3 RD币</font></p>

runlywell

我用的是ov7670 的sensor ， jjyy讲的有道理，jjyy请你详细的解释一下好吗？我想知道该怎么解决，谢谢！

chengsean

jjyy is right. YUV is related to color not edge.

Does your image is after downsample ?
If your image is after downsample, then this may be usual.
How to decrease this effect ? You can check your sensor to see if it has bining mode.
Such as micron sensor, micron sensor has bining mode to reduce this effect.

chiefhe

楼主,我建议你把0x1b寄存器改一下,如果是1就改成0,如果是0改成1.
楼上的估计理解错了：）
YUV配对错误会引起颜色错误，也可能造成锯齿！
颜色错误就不说了，大家都知道。
锯齿效果产生过程如下

例如原始数据如下：
Y0 U0 Y1 V0    Y2 U2 Y3 V2
一个clk延时后同步得到：（可能有多种情况产生延时）
U0 Y1 V0 Y2    U2 Y3 V2 Y4
Y和UV顺序交换：（7670有这种设置的寄存器）
Y1 U0 Y2 V0    Y3 U2 Y4 V2
这时候就一定会有锯齿。

楼主贴的图片不是全尺寸，如果是downsample下来得到，有锯齿不奇怪。
最好把全尺寸铁上来看看。[em25]

chiefhe

<DIV class=quote><B>以下是引用<I>jjyy</I>在2007-6-20 21:28:00的发言：</B>
if YUV components not matches each other, you should see wrong color not 锯齿

<P align=right><FONT color=red>+3 RD币</FONT></P></DIV>



锯齿可以用 zigzag

chengsean

Y0 U0 Y1 V0    Y2 U2 Y3 V2
一个clk延时后同步得到：（可能有多种情况产生延时）
U0 Y1 V0 Y2    U2 Y3 V2 Y4
Y和UV顺序交换：（7670有这种设置的寄存器）
Y1 U0 Y2 V0    Y3 U2 Y4 V2
这时候就一定会有锯齿。

from your opinion, his image will have a strange line on each end line.
because each line end will have one pixel from the next line start pixel.
But i can see this strange line one each line end.

chiefhe

<DIV class=quote><B>以下是引用<I>chengsean</I>在2007-6-21 14:01:48的发言：</B>
Y0 U0 Y1 V0    Y2 U2 Y3 V2
一个clk延时后同步得到：（可能有多种情况产生延时）
U0 Y1 V0 Y2    U2 Y3 V2 Y4
Y和UV顺序交换：（7670有这种设置的寄存器）
Y1 U0 Y2 V0    Y3 U2 Y4 V2
这时候就一定会有锯齿。

from your opinion, his image will have a strange line on each end line.
because each line end will have one pixel from the next line start pixel.
But i can see this strange line one each line end.
</DIV>


sensor 输出一行不一定是正好640像素,往往是多几个.

runlywell

谢谢各位，问题已经解掉，是edge 的问题，把sharpness调低就好了

runlywell

要做一个新的案子，不知道有哪位兄弟用过ov7720吗？请留下联系方式大家交流一下

wfdragon

to chengsean:
                    "micron sensor has bining mode to reduce this effect. "
                    bining mode???   我在micron的datasheet上没看到啊，可以细说么？[em12][em12][em12]

chengsean

To  chiefhe
If you mean the output is bayer pattern format, it will make sense for more than 640
pixels.
Because the ISP will need more pixel to process.  
But the output is YUV format, this mean the sensor has processed by ISP.
It can't output more than 640 pixel or it will cause many trouble for backend ICs.
Many backend ICs don't sync by the horizontal signal when they receive the YUYV data.
The receive the data by the size of the image not the horizontal signal. If the ISP
output the pixel is not actually 640 pixel. The backend ICs will don't know how to
process it.

To wfdragon:
Sorry I typo It is "binning mode " in Micron 2M datasheet

chiefhe

<DIV class=quote><B>以下是引用<I>chengsean</I>在2007-6-21 16:45:48的发言：</B>
To  chiefhe
If you mean the output is bayer pattern format, it will make sense for more than 640
pixels.
Because the ISP will need more pixel to process.  
But the output is YUV format, this mean the sensor has processed by ISP.
It can't output more than 640 pixel or it will cause many trouble for backend ICs.
Many backend ICs don't sync by the horizontal signal when they receive the YUYV data.
The receive the data by the size of the image not the horizontal signal. If the ISP
output the pixel is not actually 640 pixel. The backend ICs will don't know how to
process it.

To wfdragon:
Sorry I typo It is "binning mode " in Micron 2M datasheet


</DIV>



谢谢!
反正我遇到过这种情况.
改变PCLK即可消除配对错误引起的锯齿.
有条件你可以自己做实验.