EP03_03 — 🎭 Image Inversion (Photographic Negative)

3.14.3 EP03_03 🎭 Image Inversion (Photographic Negative)

In radiology, X-ray images are traditionally viewed as negatives: bones appear in black on a white background. The photographic negative operation is routinely applied in PACS (Picture Archiving and Communication Systems) to facilitate the detection of fractures and bone densities.

See Figure 3.28 for a simulation of this EP.

3.14.3.1 📋 Implementation Guidelines

Dimensions: Read the integers \(L\) (rows) and \(C\) (columns).
Data: Read the integer values of the original matrix.
Mapping: For each pixel \(p\), compute the negative:

\[p' = 255 - p\]

Output: Display the resulting matrix \(L \times C\).

3.14.3.2 📌 Computational Constraints

No clipping required: The result of \(255 - p\) with \(p \in [0, 255]\) is always \(\in [0, 255]\).
Integer type: The output must consist of integer values.
Logical equivalence: The operation is identical to the bitwise NOT (mm.bnot) on 8-bit images.

3.14.3.3 🧠 Theoretical Foundation

Original Pixel \(p\)	Negative Pixel \(p'\)	Observation
0 (black)	255 (white)	Total inversion
128 (medium gray)	127 (medium gray)	Central value
255 (white)	0 (black)	Total inversion

3.14.3.4 📦 Input and Output Specification (VPL)

Input:

Line 1: Integer \(L\).
Line 2: Integer \(C\).
Following lines: Integer elements of the original matrix.

Output:

Negative matrix with \(L\) rows and \(C\) columns.

3.14.3.5 📌 Examples

Input	Output	Observation
1 4 0 128 200 255	255 127 55 0	Inversion of each pixel
2 2 10 20 30 40	245 235 225 215	Inverted 2x2 matrix

🎭 Simulator EP03_03: Photographic Negative (Inversion) p' = 255 − p

Observe the complementary intensity inversion: dark tones become light and light tones become dark by subtracting each pixel from the maximum value of 255.

Original Input (p)

Negative (p' = 255 − p)

      Formula applied: p' = 255 − p

Figure 3.28: EP03_03 Simulator: Image Inversion — Photographic Negative (p’ = 255 − p)

%%writefile EP03_03.py
# Python code

Overwriting EP03_03.py

TestSuite("EP03_03.py").run()

✔️ EP03_03.cases already exists in casos/
📋 5 case(s) loaded from casos/EP03_03.cases

🔍 Testing Python: EP03_03.py
⚠️ EP03_03.py: Empty file (fewer than 3 lines). Tests skipped.