How to identify the correct coordinates for cropping image

[opencvnoob]

I am using a face detection library(retina-face) to detect face on the following image

The library being used is retina-face which gives bounding box coordinates in the format (x1,y1,x2,y2).
The Bounding box for the face is as follows
face_area=[242, 92, 269, 129]

Now,when I run the following part of the code,I am able to draw the bounding box on the image to represent the face

img=cv2.imread('model_2_0.jpg')
img=cv2.cvtColor(img,cv2.COLOR_BGR2RGB)
cv2.rectangle(img,(face_area[2],face_area[3]),(face_area[0],face_area[1]),(255,0,0),1)

The result of this is as follows

But when I use slicing to just obtain the face part of the image either I run into zero-sized array error or I get an incorrect result.
I am trying to crop as follows

face=img[face_area[1]:face_area[0],face_area[3]:face_area[2])

The incorrect crop is shown below

Any idea what I am doing wrong here,and is there a better way to crop rather than using slicing

[berak]

you just got the order of the coords wrong,
if you get (x1, y1, x2, y2) from the detection, the correct numpy slice is::

img[y1:y2, x1:x2] 

also your cv2.rectangle() coords should better be:

(x1,y1), (x2,y2)

[opencvnoob]

Thanks for the tip,I was able to get the result.On a side note the cropped image tends to be extremely coarse as shown below

I am currently upsampling it using cv2.pyrUp and then resize it to (256,256) to get this image

Would you recommend that’s the correct approach. I am looking for a better image where the eyes can be clearly seen as shown in the original image