Image Enhancement: is the process of mainpulating am
image so that the result is more suitable than the original. - The Enhancement techniques:

The mask or neighborhood: T is applied at each location (x,y) to produce the output g at that location.

2- Spatial filter
Called mask, kernal, tamplate or window
نستعمل هذه الطريقة للصور الأكبر حجما

1- Intensity transformation.
- Neighborhood of size 1×1
تكون للصور ذات الحجم 1×1 من اجل التخلص من يعض العيوب مثلا بعد تكبير الصورة نجد بعض التشويش فنستخدم نفس المعادلة الماضية ولكن نعوضها بطريقة أخرى
S = T (r)

Two approach of intensity transformation

Piecewise linear transformation functiions

Disadvantages

1- Their specification requires
more user input
تتطلب من المستخدم مدخلات كثيرة

Advantages

1- The form of
piecewise is complex

2- Some practical implementation
can be formulated only as piecewise
functions.

Types

1- Constrast streching,
thresholding

Reasons of this:
1- poor illumination
2- lack of dynamic range in the imaging sensor
3- wrong setting of alens aperture during image aquistion

why or what the idea behined constrast stretching:
To incrase the dynamic range of the gray levels by making the pixels with dark intensities darker and the bright onse more brighter (higher constrast image)

its functions:
- crate a binary image
- convert pixels with dark intensities into black and the bright pixels into white.
pixels above the threshold is considred bright and below it is considred dark

after constrast streching
(r1, s1) = (r min, 0 ), (r2, s2), = (r max, L-1)

2- Gray-Level slicing
- for intensity-level slicing

3- Bit-plane slicing

Basic intensirty transformation

1- Linear
negative and identity

S = L - 1 - r

Benefits

1- Produce an equivalent of
a photographic negative

2- Enhances white or gray
detail embedded in dark regions
يوضح لنا تفاصيل الصورة خصوصا درجات الأبيض والرمادي

2- log arithmic
log and invers log

S = C log (1 + r)
C is a constant
r >= 0
used for expand the dark color

1- It maps a narrow range of
low gray-level in the input
image into a wider range of
output level.

2- THe opposit is true of
higher values of input levels.
أي ان العكس صحيح ان القيم تكون اعلى في مستويات المدهلات

3- Used to expand the values
of dark pixels in an image while
compressing the higher-level values.
توسع البكسل الغامقة في حين تضغط القيم في مستوى أعلى

4- The opposit is true of the
invers log.

5- The power-law transformation are
much more versatile for this purpose
then the log transformation.

3- Power
n'th power and n'th root

S = Cr ^ y
y is Gammaتأثيرها: كلما زادت قيمتها تغمق وكلما قلت قيمتها تفتح اكثر

if y < 1 نفتح الصورة
if y > 1 نغمق الصورة
if y = 1 so it is entity
C = r = 1