Why Camera.Render() different than "Camera Preview"??

I see the "camera preview" looks perfect and the colors and brightness appear exactly as I would hope.

But when I use `camera.render()` to save the rendertexture to a file, the saved image is always super dark and looks completely different than the "camera preview".



Here is the code I use to create the image texture:

Code (csharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using System.IO;
5.  
6. #if UNITY_EDITOR
7. using UnityEditor;
8.  
9. [CustomEditor(typeof(TakeScreenshot))]
10. class TakeScreenshotEditor : Editor {
11.    public override void OnInspectorGUI() {
12.        TakeScreenshot baseScript = (TakeScreenshot)target;
13.        if(GUILayout.Button("Take Screenshot")) {
14.            var folder = Path.Combine( Application.dataPath, "Screenshots");
15.            if (!Directory.Exists (folder)) {
16.                Directory.CreateDirectory (folder);
17.            }
18.  
19.            var path = Path.Combine (folder, "screenshot.png");
20.            Debug.Log (path);
21.            baseScript.CamCapture(path);
22.        }
23.  
24.        if(GUILayout.Button("Set Frustum To Scene Object")) {
25.            baseScript.SetFrustumToSceneObject();
26.        }
27.  
28.        if(GUILayout.Button("Evaluate Curve")) {
29.            if (baseScript.t > 1) {
30.                baseScript.t = 0;
31.            }
32.  
33.            baseScript.EvaluateCurve(baseScript.m_sceneObject, baseScript.t);
34.            baseScript.t += 0.025f;
35.        }
36.        DrawDefaultInspector ();
37.    }
38. }
39. /*Add this script to any camera which also has a randertexture*/
40. [ExecuteInEditMode]
41. public class TakeScreenshot : MonoBehaviour {
42.  
43.    public Camera m_camera { get {return GetComponent<Camera>();} }
44.  
45.  
46.     public Texture2D CamCapture()
47.    {
48.        m_camera.Render();
49.  
50.        Texture2D image = new Texture2D(m_camera.targetTexture.width, m_camera.targetTexture.height);
51.        image.ReadPixels(new Rect(0, 0, m_camera.targetTexture.width, m_camera.targetTexture.height), 0, 0);
52.        image.Apply();
53.  
54.        return image;
55.    }
56.  
57.    public void CamCapture(string destPath)
58.    {
59.        RenderTexture currentRT = RenderTexture.active;
60.        RenderTexture.active = m_camera.targetTexture;
61.  
62.        Texture2D image = CamCapture ();
63.  
64.        RenderTexture.active = currentRT;
65.  
66.        var Bytes = image.EncodeToPNG();
67.        DestroyImmediate(image);
68.  
69.        var destDir = Path.GetDirectoryName (destPath);
70.        if (!Directory.Exists (destDir)) {
71.            Directory.CreateDirectory (destDir);
72.        }
73.        File.WriteAllBytes(destPath, Bytes);
74.    }
75.  
76. }

---

What's even stranger is how Unity "almost" got it when I changed the colorformat of the Rendertextur, I see the colors and brightness are correct, but yet again there is a bug and Unity generates artifacts in the saved image:
I notice that one of my UI panels is showing in the image - it's just a black space if I take screenshot while game is running.

I can't get Unity to work correctly, no matter how I change lighting settings, or camera settings, or rendertexture settings, or meshrenderer settings, the final image is always darker than the preview.

What should I do? All I want to do is save an image exactly as it appears in the render preview, this should be easy, what am I doing wrong?

 

I just tested this: SaveRenderTextureToFile.cs script from a GitHub member to verify if I was making a mistake. I get the exact same result in all of my projects where the selected rendertexture saves as a png that's too dark to see.

Is this a bug? Has it ever been reported before? I am currently using Unity 2019.2.4f1 - win10.
But I have been having this issue since Unity 5. How can I fix this??

 

I just changed the color space and the issue flipped!! Now the saved file is bright and colorful but the camera preview is too dark to see?

How can i have the camera preview and the rendertexture look exactly the same?

 

I have no Idea why Unity trying to flip color spaces.. but I just solved my issue by manually converting the colorspace for each pixel.



Here's the updated code:

Code (csharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using System.IO;
5.  
6. #if UNITY_EDITOR
7. using UnityEditor;
8.  
9. [CustomEditor(typeof(TakeScreenshot))]
10. class TakeScreenshotEditor : Editor {
11.    public override void OnInspectorGUI() {
12.        TakeScreenshot baseScript = (TakeScreenshot)target;
13.        if(GUILayout.Button("Take Screenshot")) {
14.            var folder = Path.Combine( Application.dataPath, "Screenshots");
15.            if (!Directory.Exists (folder)) {
16.                Directory.CreateDirectory (folder);
17.            }
18.  
19.            var path = Path.Combine (folder, "screenshot.png");
20.            Debug.Log (path);
21.            baseScript.CamCapture(path);
22.        }
23.  
24.        if(GUILayout.Button("Set Frustum To Scene Object")) {
25.            baseScript.SetFrustumToSceneObject();
26.        }
27.  
28.        if(GUILayout.Button("Evaluate Curve")) {
29.            if (baseScript.t > 1) {
30.                baseScript.t = 0;
31.            }
32.  
33.            baseScript.EvaluateCurve(baseScript.m_sceneObject, baseScript.t);
34.            baseScript.t += 0.025f;
35.        }
36.        DrawDefaultInspector ();
37.    }
38. }
39. /*Add this script to any camera which also has a randertexture*/
40. [ExecuteInEditMode]
41. public class TakeScreenshot : MonoBehaviour {
42.  
43.     public Camera m_camera { get {return GetComponent<Camera>();} }
44.  
45.  
46.     public void FixColorSpace(Texture2D image)
47.     {
48.         for (int y = 0; y < image.height; y++)
49.         {
50.             for (int x = 0; x < image.width; x++)
51.             {
52.                 image.SetPixel(x, y, new Color(
53.                     Mathf.Pow(image.GetPixel(x, y).r, 1f / 2.2f),
54.                     Mathf.Pow(image.GetPixel(x, y).g, 1f / 2.2f),
55.                     Mathf.Pow(image.GetPixel(x, y).b, 1f / 2.2f),
56.                     Mathf.Pow(image.GetPixel(x, y).a, 1f / 2.2f)
57.                 ));
58.             }
59.         }
60.     }
61.  
62.     public Texture2D CamCapture()
63.    {
64.         m_camera.Render();
65.  
66.         Texture2D image = new Texture2D(m_camera.targetTexture.width, m_camera.targetTexture.height);
67.        image.ReadPixels(new Rect(0, 0, m_camera.targetTexture.width, m_camera.targetTexture.height), 0, 0);
68.  
69.         FixColorSpace(image);
70.         image.Apply();
71.  
72.        return image;
73.    }
74.  
75.    public void CamCapture(string destPath)
76.    {
77.        RenderTexture currentRT = RenderTexture.active;
78.        RenderTexture.active = m_camera.targetTexture;
79.  
80.        Texture2D image = CamCapture ();
81.  
82.        RenderTexture.active = currentRT;
83.  
84.        var Bytes = image.EncodeToPNG();
85.        DestroyImmediate(image);
86.  
87.        var destDir = Path.GetDirectoryName (destPath);
88.        if (!Directory.Exists (destDir)) {
89.            Directory.CreateDirectory (destDir);
90.        }
91.        File.WriteAllBytes(destPath, Bytes);
92.    }
93.  
94. }

Is this workaround the only way to fix Unity's color space bug? It runs for all pixels (which is very expensive) and I don't like it much.