RGB-waarden uit een afbeelding halen

Er zijn grofweg drie stappen om de dominante kleuren in een afbeelding te vinden:

Haal RGB-waarden op in drie lijsten.
Voer k-means clustering uit op geschaalde RGB-waarden.
Toon de kleuren van de clustercentra.

Om RGB-waarden op te halen gebruiken we de functie imread() van de image-klasse in matplotlib. Lege lijsten, r, g en b, zijn al geïnitialiseerd.

Voor het bepalen van dominante kleuren gebruiken we de volgende afbeelding.

Deze oefening maakt deel uit van de cursus

Clusteranalyse in Python

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Oefeninstructies

Importeer de image-klasse van matplotlib.
Lees de afbeelding in met de functie imread() en print de afmetingen van de resulterende matrix.
Sla de waarden voor de drie kleuren van alle pixels op in de lijsten r, g en b.

Praktische interactieve oefening

Probeer deze oefening eens door deze voorbeeldcode in te vullen.

# Import image class of matplotlib
____ as img

# Read batman image and print dimensions
batman_image = ____('batman.jpg')
print(____)

# Store RGB values of all pixels in lists r, g and b
for ____:
    for temp_r, temp_g, temp_b in ____:
        r.append(temp_r)
        g.append(temp_g)
        b.append(temp_b)

Code bewerken en uitvoeren

Deze oefening maakt deel uit van de cursus

Clusteranalyse in Python

SkillTag.level.intermediateSkillTag.label

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Before you are ready to classify news articles, you need to be introduced to the basics of clustering. This chapter familiarizes you with a class of machine learning algorithms called unsupervised learning and then introduces you to clustering, one of the popular unsupervised learning algorithms. You will know about two popular clustering techniques - hierarchical clustering and k-means clustering. The chapter concludes with basic pre-processing steps before you start clustering data.

Exercise 1: Unsupervised learning: basics Exercise 2: Unsupervised learning in real world Exercise 3: Pokémon sightings Exercise 4: Basics of cluster analysis Exercise 5: Pokémon sightings: hierarchical clustering Exercise 6: Pokémon sightings: k-means clustering Exercise 7: Data preparation for cluster analysis Exercise 8: Normalize basic list data Exercise 9: Visualize normalized data Exercise 10: Normalization of small numbers Exercise 11: FIFA 18: Normalize data

This chapter focuses on a popular clustering algorithm - hierarchical clustering - and its implementation in SciPy. In addition to the procedure to perform hierarchical clustering, it attempts to help you answer an important question - how many clusters are present in your data? The chapter concludes with a discussion on the limitations of hierarchical clustering and discusses considerations while using hierarchical clustering.

Exercise 1: Basics of hierarchical clustering Exercise 2: Hierarchical clustering: ward method Exercise 3: Hierarchical clustering: single method Exercise 4: Hierarchical clustering: complete method Exercise 5: Visualize clusters Exercise 6: Visualize clusters with matplotlib Exercise 7: Visualize clusters with seaborn Exercise 8: How many clusters?Exercise 9: Create a dendrogram Exercise 10: How many clusters in comic con data?Exercise 11: Limitations of hierarchical clustering Exercise 12: Timing run of hierarchical clustering Exercise 13: FIFA 18: exploring defenders

This chapter introduces a different clustering algorithm - k-means clustering - and its implementation in SciPy. K-means clustering overcomes the biggest drawback of hierarchical clustering that was discussed in the last chapter. As dendrograms are specific to hierarchical clustering, this chapter discusses one method to find the number of clusters before running k-means clustering. The chapter concludes with a discussion on the limitations of k-means clustering and discusses considerations while using this algorithm.

Exercise 1: Basics of k-means clustering Exercise 2: K-means clustering: first exercise Exercise 3: Runtime of k-means clustering Exercise 4: How many clusters?Exercise 5: Elbow method on distinct clusters Exercise 6: Elbow method on uniform data Exercise 7: Limitations of k-means clustering Exercise 8: Impact of seeds on distinct clusters Exercise 9: Uniform clustering patterns Exercise 10: FIFA 18: defenders revisited

Now that you are familiar with two of the most popular clustering techniques, this chapter helps you apply this knowledge to real-world problems. The chapter first discusses the process of finding dominant colors in an image, before moving on to the problem discussed in the introduction - clustering of news articles. The chapter concludes with a discussion on clustering with multiple variables, which makes it difficult to visualize all the data.

Exercise 1: Dominante kleuren in afbeeldingen Exercise 2: RGB-waarden uit een afbeelding halen

Huidige oefening

Exercise 3: Hoeveel dominante kleuren?Exercise 4: Dominante kleuren weergeven Exercise 5: Documentclustering Exercise 6: TF-IDF van filmplots Exercise 7: Toptermen in filmclusters Exercise 8: Clusteren met meerdere kenmerken Exercise 9: Clusteren met veel features Exercise 10: Basistests op clusters Exercise 11: FIFA 18: wat maakt een complete speler?Exercise 12: Tot ziens!