Add comment concerning printing {min,max}Color

As got:

```
Filtering images:   0%|▏                                                                               | 21/8156 [00:11<1:17:28,  1.75it/s]
```

datasets/raise/extract_noise.py

@@ -9,7 +9,7 @@ from tqdm import tqdm
 import csv
 import rawpy
 
-imagesFolderPath = 'flat-field/nef'
+imagesFolderPath = '/mnt/HDD0/raise'
 imagesFolderPathFileName = imagesFolderPath.replace('/', '_')
 denoiser = 'wavelet'
 npArrayFilePath = f'mean_{imagesFolderPathFileName}_{denoiser}.npy'
@@ -19,9 +19,9 @@ denoise = getattr(skimage.restoration, f'denoise_{denoiser}')
 mean = None
 numberOfImagesInMean = 0
 
-imagesFileNames = os.listdir(imagesFolderPath)
+imagesFileNames = os.listdir(imagesFolderPath + '/png')
 
-requiresRaiseFiltering = False
+requiresRaiseFiltering = True
 if requiresRaiseFiltering:
     files = {}
 
@@ -31,15 +31,17 @@ if requiresRaiseFiltering:
             file = row['File'] + '.png'
             files[file] = row
 
-    imagesFileNames = [imageFileName for imageFileName in tqdm(imagesFileNames, 'Filtering images') if files[imageFileName]['Device'] == 'Nikon D7000' and Image.open(f'{imagesFolderPath}/{imageFileName}').size == (4946, 3278)]
+    imagesFileNames = [imageFileName for imageFileName in tqdm(imagesFileNames, 'Filtering images') if files[imageFileName]['Device'] == 'Nikon D7000' and Image.open(f'{imagesFolderPath}/png/{imageFileName}').size == (4946, 3278)]
+#imagesFileNames = [f'DSC0{imageIndex}.ARW' for imageIndex in range(2807, 2911)]
 
 minColor = None
 maxColor = None
 
 def treatImage(imageFileName, computeExtremes = False):
     global mean, numberOfImagesInMean, minColor, maxColor
-    imageFilePath = f'{imagesFolderPath}/{imageFileName}'
-    if imageFileName.endswith('.NEF'):
+    imageFileName = imageFileName.replace('.png', '.NEF')
+    imageFilePath = f'{imagesFolderPath}/nef/{imageFileName}'
+    if imageFileName.endswith('.NEF') or imageFileName.endswith('.ARW'):
         with rawpy.imread(imageFilePath) as raw:
             colorDesc = raw.color_desc.decode('ascii')
             assert colorDesc == 'RGBG'
@@ -78,6 +80,11 @@ def treatImage(imageFileName, computeExtremes = False):
 for imageFileName in tqdm(imagesFileNames, 'Computing extremes of images'):
     treatImage(imageFileName, computeExtremes = True)
 
+# To skip this step next time.
+# Maybe thanks to `rawpy.RawPy` fields, possibly stating device maximal value, can avoid doing so to some extent.
+print(f'{minColor=}')
+print(f'{maxColor=}')
+
 for imageFileName in tqdm(imagesFileNames, 'Denoising images'):
     treatImage(imageFileName)