{
"cells": [
{
"cell_type": "markdown",
"id": "afbc17f0",
"metadata": {},
"source": [
"# galaxy_image\n",
"Importing an image and manipulating it.\n",
"\n",
"\n",
"\n",
"\n",
"**Author:** Valeriy Onuchin \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:38 PM."
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "ca69ba79",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:35.191507Z",
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"iopub.status.idle": "2026-05-19T20:38:35.539678Z",
"shell.execute_reply": "2026-05-19T20:38:35.539158Z"
}
},
"outputs": [],
"source": [
"TCanvas *canv = new TCanvas(\"image\", \"n4254\", 40, 40, 812, 700);\n",
"canv->ToggleEventStatus();\n",
"canv->SetRightMargin(0.2);\n",
"canv->SetLeftMargin(0.01);\n",
"canv->SetTopMargin(0.01);\n",
"canv->SetBottomMargin(0.01);"
]
},
{
"cell_type": "markdown",
"id": "99055812",
"metadata": {},
"source": [
"read the pixel data from file \"galaxy.root\"\n",
"the size of the image is 401 X 401 pixels"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "feb3f675",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:35.541567Z",
"iopub.status.busy": "2026-05-19T20:38:35.541451Z",
"iopub.status.idle": "2026-05-19T20:38:36.023439Z",
"shell.execute_reply": "2026-05-19T20:38:36.023010Z"
}
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"accessing galaxy.root file from http://root.cern/files\n"
]
}
],
"source": [
"const char *fname = \"galaxy.root\";\n",
"TFile *gal = 0;\n",
"if (!gSystem->AccessPathName(fname)) {\n",
" gal = TFile::Open(fname);\n",
"} else {\n",
" printf(\"accessing %s file from http://root.cern/files\\n\", fname);\n",
" gal = TFile::Open(Form(\"http://root.cern/files/%s\", fname));\n",
"}\n",
"if (!gal)\n",
" return;\n",
"TImage *img = (TImage *)gal->Get(\"n4254\");\n",
"img->Draw();"
]
},
{
"cell_type": "markdown",
"id": "28cbf26c",
"metadata": {},
"source": [
"open the color editor"
]
},
{
"cell_type": "markdown",
"id": "9ad3aa52",
"metadata": {},
"source": [
"zoom the image"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "fb210d32",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:36.025010Z",
"iopub.status.busy": "2026-05-19T20:38:36.024900Z",
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"shell.execute_reply": "2026-05-19T20:38:36.236096Z"
}
},
"outputs": [],
"source": [
"img->Zoom(80, 80, 250, 250);"
]
},
{
"cell_type": "markdown",
"id": "8c6a844d",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "8762540b",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:36.238404Z",
"iopub.status.busy": "2026-05-19T20:38:36.238293Z",
"iopub.status.idle": "2026-05-19T20:38:36.452204Z",
"shell.execute_reply": "2026-05-19T20:38:36.451858Z"
}
},
"outputs": [
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],
"source": [
"gROOT->GetListOfCanvases()->Draw()"
]
}
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